diff --git a/compiler/ballerina-lang/src/main/java/org/ballerinalang/util/diagnostic/DiagnosticCode.java b/compiler/ballerina-lang/src/main/java/org/ballerinalang/util/diagnostic/DiagnosticCode.java
index 1fb8c5fcc0ba..4a16578615b8 100644
--- a/compiler/ballerina-lang/src/main/java/org/ballerinalang/util/diagnostic/DiagnosticCode.java
+++ b/compiler/ballerina-lang/src/main/java/org/ballerinalang/util/diagnostic/DiagnosticCode.java
@@ -72,6 +72,7 @@ public enum DiagnosticCode {
     ABSTRACT_OBJECT_FUNCTION_CANNOT_HAVE_BODY("abstract.object.function.cannot.have.body"),
     PRIVATE_OBJECT_CONSTRUCTOR("private.object.constructor"),
     PRIVATE_FIELD_ABSTRACT_OBJECT("private.field.abstract.object"),
+    FIELD_WITH_DEFAULT_VALUE_ABSTRACT_OBJECT("field.with.default.value.abstract.object"),
     PRIVATE_FUNC_ABSTRACT_OBJECT("private.function.abstract.object"),
     EXTERN_FUNC_ABSTRACT_OBJECT("extern.function.abstract.object"),
     RESOURCE_FUNCTION_CANNOT_BE_EXTERN("resource.function.cannot.be.extern"),
@@ -104,6 +105,7 @@ public enum DiagnosticCode {
     EXPLICIT_WORKER_CANNOT_BE_DEFAULT("explicit.worker.cannot.be.default"),
     INVALID_MULTIPLE_FORK_JOIN_SEND("worker.multiple.fork.join.send"),
     INCOMPATIBLE_TYPE_REFERENCE("incompatible.type.reference"),
+    INCOMPATIBLE_TYPE_REFERENCE_NON_PUBLIC_MEMBERS("incompatible.type.reference.non.public.members"),
     INCOMPATIBLE_RECORD_TYPE_REFERENCE("incompatible.record.type.reference"),
     REDECLARED_TYPE_REFERENCE("redeclared.type.reference"),
     REDECLARED_FUNCTION_FROM_TYPE_REFERENCE("redeclared.function.from.type.reference"),
diff --git a/compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/semantics/analyzer/SemanticAnalyzer.java b/compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/semantics/analyzer/SemanticAnalyzer.java
index 7ebf19c8232a..5332dbbb1fae 100644
--- a/compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/semantics/analyzer/SemanticAnalyzer.java
+++ b/compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/semantics/analyzer/SemanticAnalyzer.java
@@ -377,8 +377,14 @@ public void visit(BLangObjectTypeNode objectTypeNode) {
         boolean isAbstract = objectTypeNode.flagSet.contains(Flag.ABSTRACT);
         objectTypeNode.fields.forEach(field -> {
             analyzeDef(field, objectEnv);
-            if (isAbstract && field.flagSet.contains(Flag.PRIVATE)) {
-                this.dlog.error(field.pos, DiagnosticCode.PRIVATE_FIELD_ABSTRACT_OBJECT, field.symbol.name);
+            if (isAbstract) {
+                if (field.flagSet.contains(Flag.PRIVATE)) {
+                    this.dlog.error(field.pos, DiagnosticCode.PRIVATE_FIELD_ABSTRACT_OBJECT, field.symbol.name);
+                }
+
+                if (field.expr != null) {
+                    this.dlog.error(field.expr.pos, DiagnosticCode.FIELD_WITH_DEFAULT_VALUE_ABSTRACT_OBJECT);
+                }
             }
         });
 
diff --git a/compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/semantics/analyzer/SymbolEnter.java b/compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/semantics/analyzer/SymbolEnter.java
index 08547d5e4ac0..3ed1bd6932c5 100644
--- a/compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/semantics/analyzer/SymbolEnter.java
+++ b/compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/semantics/analyzer/SymbolEnter.java
@@ -58,6 +58,7 @@
 import org.wso2.ballerinalang.compiler.semantics.model.types.BField;
 import org.wso2.ballerinalang.compiler.semantics.model.types.BFutureType;
 import org.wso2.ballerinalang.compiler.semantics.model.types.BInvokableType;
+import org.wso2.ballerinalang.compiler.semantics.model.types.BObjectType;
 import org.wso2.ballerinalang.compiler.semantics.model.types.BRecordType;
 import org.wso2.ballerinalang.compiler.semantics.model.types.BServiceType;
 import org.wso2.ballerinalang.compiler.semantics.model.types.BStructureType;
@@ -1284,6 +1285,7 @@ private void defineMembers(List<BLangTypeDefinition> typeDefNodes, SymbolEnv pkg
                     defineNode(f, objMethodsEnv);
                 });
 
+                List<String> referencedFunctions = new ArrayList<>();
                 // Add the attached functions of the referenced types to this object.
                 // Here it is assumed that all the attached functions of the referred type are
                 // resolved by the time we reach here. It is achieved by ordering the typeDefs
@@ -1295,7 +1297,7 @@ private void defineMembers(List<BLangTypeDefinition> typeDefNodes, SymbolEnv pkg
 
                     List<BAttachedFunction> functions = ((BObjectTypeSymbol) typeRef.type.tsymbol).attachedFuncs;
                     for (BAttachedFunction function : functions) {
-                        defineReferencedFunction(typeDef, objMethodsEnv, typeRef, function);
+                        defineReferencedFunction(typeDef, objMethodsEnv, typeRef, function, referencedFunctions);
                     }
                 }
             } else if (typeDef.symbol.kind == SymbolKind.RECORD) {
@@ -1688,6 +1690,7 @@ private void createDummyTypeDefSymbol(TypeDefinition typeDefNode, SymbolEnv env)
 
     private void resolveReferencedFields(BLangStructureTypeNode structureTypeNode, SymbolEnv typeDefEnv) {
         List<BSymbol> referencedTypes = new ArrayList<>();
+        List<BLangType> invalidTypeRefs = new ArrayList<>();
         // Get the inherited fields from the type references
         structureTypeNode.referencedFields = structureTypeNode.typeRefs.stream().flatMap(typeRef -> {
             BType referredType = symResolver.resolveTypeNode(typeRef, typeDefEnv);
@@ -1698,13 +1701,28 @@ private void resolveReferencedFields(BLangStructureTypeNode structureTypeNode, S
             // Check for duplicate type references
             if (referencedTypes.contains(referredType.tsymbol)) {
                 dlog.error(typeRef.pos, DiagnosticCode.REDECLARED_TYPE_REFERENCE, typeRef);
+                invalidTypeRefs.add(typeRef);
                 return Stream.empty();
             }
 
-            if (structureTypeNode.type.tag == TypeTags.OBJECT && (referredType.tag != TypeTags.OBJECT || !Symbols
-                    .isFlagOn(referredType.tsymbol.flags, Flags.ABSTRACT))) {
-                dlog.error(typeRef.pos, DiagnosticCode.INCOMPATIBLE_TYPE_REFERENCE, typeRef);
-                return Stream.empty();
+            if (structureTypeNode.type.tag == TypeTags.OBJECT) {
+                if (referredType.tag != TypeTags.OBJECT ||
+                        !Symbols.isFlagOn(referredType.tsymbol.flags, Flags.ABSTRACT)) {
+                    dlog.error(typeRef.pos, DiagnosticCode.INCOMPATIBLE_TYPE_REFERENCE, typeRef);
+                    invalidTypeRefs.add(typeRef);
+                    return Stream.empty();
+                }
+
+                BObjectType objectType = (BObjectType) referredType;
+                if (structureTypeNode.type.tsymbol.owner != referredType.tsymbol.owner) {
+                    if (objectType.fields.stream().anyMatch(field -> !Symbols.isPublic(field.symbol)) ||
+                            ((BObjectTypeSymbol) objectType.tsymbol).attachedFuncs.stream()
+                                    .anyMatch(func -> !Symbols.isPublic(func.symbol))) {
+                        dlog.error(typeRef.pos, DiagnosticCode.INCOMPATIBLE_TYPE_REFERENCE_NON_PUBLIC_MEMBERS, typeRef);
+                        invalidTypeRefs.add(typeRef);
+                        return Stream.empty();
+                    }
+                }
             }
 
             if (structureTypeNode.type.tag == TypeTags.RECORD && referredType.tag != TypeTags.RECORD) {
@@ -1724,15 +1742,23 @@ private void resolveReferencedFields(BLangStructureTypeNode structureTypeNode, S
                 return var;
             });
         }).collect(Collectors.toList());
+        structureTypeNode.typeRefs.removeAll(invalidTypeRefs);
     }
 
     private void defineReferencedFunction(BLangTypeDefinition typeDef, SymbolEnv objEnv, BLangType typeRef,
-                                          BAttachedFunction referencedFunc) {
+                                          BAttachedFunction referencedFunc, List<String> referencedFunctions) {
+        String referencedFuncName = referencedFunc.funcName.value;
         Name funcName = names.fromString(
-                Symbols.getAttachedFuncSymbolName(typeDef.symbol.name.value, referencedFunc.funcName.value));
+                Symbols.getAttachedFuncSymbolName(typeDef.symbol.name.value, referencedFuncName));
         BSymbol matchingObjFuncSym = symResolver.lookupSymbol(objEnv, funcName, SymTag.VARIABLE);
 
         if (matchingObjFuncSym != symTable.notFoundSymbol) {
+            if (referencedFunctions.contains(referencedFuncName)) {
+                dlog.error(typeRef.pos, DiagnosticCode.REDECLARED_SYMBOL, referencedFuncName);
+                return;
+            }
+            referencedFunctions.add(referencedFuncName);
+
             if (Symbols.isFunctionDeclaration(matchingObjFuncSym) && Symbols.isFunctionDeclaration(
                     referencedFunc.symbol)) {
                 Optional<BLangFunction> matchingFunc = ((BLangObjectTypeNode) typeDef.typeNode)
@@ -1791,7 +1817,10 @@ private boolean hasSameFunctionSignature(BInvokableSymbol attachedFuncSym, BInvo
 
         List<BVarSymbol> params = referencedFuncSym.params;
         for (int i = 0; i < params.size(); i++) {
-            if (!params.get(i).name.value.equals(attachedFuncSym.params.get(i).name.value)) {
+            BVarSymbol referencedFuncParam = params.get(i);
+            BVarSymbol attachedFuncParam = attachedFuncSym.params.get(i);
+            if (!referencedFuncParam.name.value.equals(attachedFuncParam.name.value) ||
+                    !hasSameVisibilityModifier(referencedFuncParam.flags, attachedFuncParam.flags)) {
                 return false;
             }
         }
@@ -1822,7 +1851,8 @@ private String getCompleteFunctionSignature(BInvokableSymbol funcSymbol) {
         signatureBuilder.append(visibilityModifier).append("function ")
                 .append(funcSymbol.name.value.split("\\.")[1]);
 
-        funcSymbol.params.forEach(param -> paramListBuilder.add(param.type.toString() + " " + param.name.value));
+        funcSymbol.params.forEach(param -> paramListBuilder.add(
+                (Symbols.isPublic(param) ? "public " : "") + param.type.toString() + " " + param.name.value));
 
         if (funcSymbol.restParam != null) {
             paramListBuilder.add(((BArrayType) funcSymbol.restParam.type).eType.toString() + "... " +
diff --git a/compiler/ballerina-lang/src/main/resources/compiler.properties b/compiler/ballerina-lang/src/main/resources/compiler.properties
index 5067a32af7fd..b1b12b46247a 100644
--- a/compiler/ballerina-lang/src/main/resources/compiler.properties
+++ b/compiler/ballerina-lang/src/main/resources/compiler.properties
@@ -718,6 +718,9 @@ error.private.object.constructor=\
 error.private.field.abstract.object=\
   abstract object field: ''{0}'' can not be declared as private
 
+error.field.with.default.value.abstract.object=\
+  fields with default values are not yet supported with abstract objects
+
 error.private.function.abstract.object=\
   interface function: ''{0}'' of abstract object ''{1}'' can not be declared as private
 
@@ -742,6 +745,9 @@ error.extern.function.abstract.object=\
 error.incompatible.type.reference=\
   incompatible types: ''{0}'' is not an abstract object
 
+error.incompatible.type.reference.non.public.members=\
+  incompatible type reference ''{0}'': a referenced object cannot have non-public fields or methods
+
 error.incompatible.record.type.reference=\
   incompatible types: ''{0}'' is not a record
 
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/delay-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/delay-window.bal
index 8f352a3fb1ae..06a849ecdf8e 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/delay-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/delay-window.bal
@@ -142,7 +142,7 @@ public type DelayWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/external-time-batch-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/external-time-batch-window.bal
index 2890ab138ae2..df828796fc44 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/external-time-batch-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/external-time-batch-window.bal
@@ -256,7 +256,7 @@ public type ExternalTimeBatchWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/external-time-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/external-time-window.bal
index d837d0b90070..fe2705cb46f1 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/external-time-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/external-time-window.bal
@@ -137,7 +137,7 @@ public type ExternalTimeWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/hopping-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/hopping-window.bal
index e97362400be7..68e34f64823f 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/hopping-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/hopping-window.bal
@@ -158,7 +158,7 @@ public type HoppingWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/length-batch-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/length-batch-window.bal
index 4d0853b67491..456bf268a98a 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/length-batch-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/length-batch-window.bal
@@ -134,7 +134,7 @@ public type LengthBatchWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/length-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/length-window.bal
index c271af132e9c..819ffd2c87db 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/length-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/length-window.bal
@@ -100,7 +100,7 @@ public type LengthWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/sort-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/sort-window.bal
index 2901dddb6545..f4bbeb7e8b11 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/sort-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/sort-window.bal
@@ -194,7 +194,7 @@ public type SortWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/time-accumulating-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/time-accumulating-window.bal
index abf004ec65c7..b948769810d1 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/time-accumulating-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/time-accumulating-window.bal
@@ -140,7 +140,7 @@ public type TimeAccumulatingWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/time-batch-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/time-batch-window.bal
index c2dffee9a863..67aa77ca691f 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/time-batch-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/time-batch-window.bal
@@ -142,7 +142,7 @@ public type TimeBatchWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/time-length-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/time-length-window.bal
index 3018f688816a..0e93976afa46 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/time-length-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/time-length-window.bal
@@ -160,7 +160,7 @@ public type TimeLengthWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/time-order-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/time-order-window.bal
index b5296219ab2a..375fa75b0ca4 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/time-order-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/time-order-window.bal
@@ -189,7 +189,7 @@ public type TimeOrderWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/time-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/time-window.bal
index e8c5f37d70aa..ab67ee3844fd 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/time-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/time-window.bal
@@ -139,7 +139,7 @@ public type TimeWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/streams/src/main/ballerina/src/streams/window/unique-length-window.bal b/stdlib/streams/src/main/ballerina/src/streams/window/unique-length-window.bal
index 767ee7503b9a..bc5240ed8719 100644
--- a/stdlib/streams/src/main/ballerina/src/streams/window/unique-length-window.bal
+++ b/stdlib/streams/src/main/ballerina/src/streams/window/unique-length-window.bal
@@ -168,7 +168,7 @@ public type UniqueLengthWindow object {
     public function getCandidateEvents(
                         StreamEvent originEvent,
                         (function (map<anydata> e1Data, map<anydata> e2Data) returns boolean)? conditionFunc,
-                        boolean isLHSTrigger = true)
+                        public boolean isLHSTrigger = true)
                         returns @tainted [StreamEvent?, StreamEvent?][] {
         [StreamEvent?, StreamEvent?][] events = [];
         int i = 0;
diff --git a/stdlib/transactions/src/main/ballerina/src/transactions/2pc_participant.bal b/stdlib/transactions/src/main/ballerina/src/transactions/2pc_participant.bal
index 722ae0c705be..c2fcdbfccf91 100644
--- a/stdlib/transactions/src/main/ballerina/src/transactions/2pc_participant.bal
+++ b/stdlib/transactions/src/main/ballerina/src/transactions/2pc_participant.bal
@@ -37,7 +37,7 @@ public type UProtocol LocalProtocol|RemoteProtocol;
 
 type Participant abstract object {
 
-    string participantId = "";
+    string participantId;
 
     function prepare(string protocol) returns [(PrepareResult|error)?, Participant];
 
diff --git a/tests/jballerina-unit-test/src/test/java/org/ballerinalang/test/object/AbstractObjectTest.java b/tests/jballerina-unit-test/src/test/java/org/ballerinalang/test/object/AbstractObjectTest.java
index 900615b01bb7..244511b02ddb 100644
--- a/tests/jballerina-unit-test/src/test/java/org/ballerinalang/test/object/AbstractObjectTest.java
+++ b/tests/jballerina-unit-test/src/test/java/org/ballerinalang/test/object/AbstractObjectTest.java
@@ -44,7 +44,7 @@ public void setup() {
     public void testAbstractObjectNegative() {
         CompileResult negativeResult = BCompileUtil.compile("test-src/object/abstract-object-negative.bal");
         int index = 0;
-        Assert.assertEquals(negativeResult.getErrorCount(), 11);
+        Assert.assertEquals(negativeResult.getErrorCount(), 12);
         BAssertUtil.validateError(negativeResult, index++, "cannot initialize abstract object 'Person1'", 3, 18);
         BAssertUtil.validateError(negativeResult, index++, "cannot initialize abstract object 'Person2'", 4, 18);
         BAssertUtil.validateError(negativeResult, index++, "cannot initialize abstract object 'Person1'", 8, 18);
@@ -61,8 +61,10 @@ public void testAbstractObjectNegative() {
                 "'Person6' can not be declared as private", 61, 5);
         BAssertUtil.validateError(negativeResult, index++, "interface function: 'getName' of abstract object 'Foo' " +
                 "can not be declared as private", 65, 5);
-        BAssertUtil.validateError(negativeResult, index,
+        BAssertUtil.validateError(negativeResult, index++,
                                   "external function: 'getName' not allowed in abstract object 'Person7'", 78, 5);
+        BAssertUtil.validateError(negativeResult, index,
+                                  "fields with default values are not yet supported with abstract objects", 83, 18);
     }
 
     @Test
diff --git a/tests/jballerina-unit-test/src/test/java/org/ballerinalang/test/object/ObjectTypeReferenceTest.java b/tests/jballerina-unit-test/src/test/java/org/ballerinalang/test/object/ObjectTypeReferenceTest.java
index 20b74f4de754..d46a0725aaea 100644
--- a/tests/jballerina-unit-test/src/test/java/org/ballerinalang/test/object/ObjectTypeReferenceTest.java
+++ b/tests/jballerina-unit-test/src/test/java/org/ballerinalang/test/object/ObjectTypeReferenceTest.java
@@ -44,7 +44,7 @@ public void setup() {
     @Test
     public void testSimpleObjectTypeReferenceNegative_1() {
         CompileResult negativeResult = BCompileUtil.compile("test-src/object/object-type-reference-1-negative.bal");
-        Assert.assertEquals(negativeResult.getErrorCount(), 22);
+        Assert.assertEquals(negativeResult.getErrorCount(), 23);
         int i = 0;
         BAssertUtil.validateError(negativeResult, i++, "uninitialized field 'age'", 27, 6);
         BAssertUtil.validateError(negativeResult, i++, "uninitialized field 'name'", 27, 6);
@@ -72,7 +72,8 @@ public void testSimpleObjectTypeReferenceNegative_1() {
                 "function through referenced type 'ObjectWithRedeclaredFunction_1'", 125, 6);
         BAssertUtil.validateError(negativeResult, i++, "redeclared symbol 'x'", 134, 6);
         BAssertUtil.validateError(negativeResult, i++, "unknown type 'Baz'", 142, 6);
-        BAssertUtil.validateError(negativeResult, i, "unknown type 'Tar'", 146, 6);
+        BAssertUtil.validateError(negativeResult, i++, "unknown type 'Tar'", 146, 6);
+        BAssertUtil.validateError(negativeResult, i, "redeclared symbol 'xyz'", 167, 6);
     }
 
     @Test
@@ -151,31 +152,51 @@ public void testTypeReferencedFunctionImplementation() {
         CompileResult result = BCompileUtil.compile("test-src/object/object_func_reference_neg.bal");
         int index = 0;
 
-        Assert.assertEquals(result.getErrorCount(), 7);
+        Assert.assertEquals(result.getErrorCount(), 8);
         BAssertUtil.validateError(result, index++,
                                   "mismatched function signatures: expected 'function test1(string aString, int " +
                                           "anInt) returns (string|error)', found 'function test1(string str, int " +
                                           "anInt)" +
-                                          " returns (string|error)'", 51, 5);
+                                          " returns (string|error)'", 53, 5);
         BAssertUtil.validateError(result, index++,
                                   "mismatched function signatures: expected 'public function test2(string aString)', " +
-                                          "found 'function test2(string aString)'", 56, 5);
+                                          "found 'function test2(string aString)'", 58, 5);
         BAssertUtil.validateError(result, index++,
                                   "mismatched function signatures: expected 'function test3(int anInt, string " +
                                           "aString, string defaultable, int def2)', found 'function test3(string " +
-                                          "aString, int anInt, string defaultable, int def2) returns string'", 59, 5);
+                                          "aString, int anInt, string defaultable, int def2) returns string'", 61, 5);
         BAssertUtil.validateError(result, index++,
                                   "mismatched function signatures: expected 'function test4(string aString, int " +
                                           "anInt, Bar... bars) returns string', found 'function test4(string aString," +
-                                          " int anInt, AnotherBar... bars) returns string'", 64, 5);
+                                          " int anInt, AnotherBar... bars) returns string'", 66, 5);
         BAssertUtil.validateError(result, index++,
                                   "mismatched function signatures: expected 'function test5(ON|OFF... status) returns" +
-                                          " Bar', found 'function test5(ON|OFF... stat) returns Bar'", 69, 5);
+                                          " Bar', found 'function test5(ON|OFF... stat) returns Bar'", 71, 5);
         BAssertUtil.validateError(result, index++,
                                   "mismatched function signatures: expected 'function test6([string,ON|OFF]... tup)'," +
-                                          " found 'function test6([string,ON|OFF]... tupl)'", 74, 5);
-        BAssertUtil.validateError(result, index,
+                                          " found 'function test6([string,ON|OFF]... tupl)'", 76, 5);
+        BAssertUtil.validateError(result, index++,
                                   "mismatched function signatures: expected 'function test7() returns ON|OFF', found " +
-                                          "'function test7(int x) returns ON|OFF'", 77, 5);
+                                          "'function test7(int x) returns ON|OFF'", 79, 5);
+        BAssertUtil.validateError(result, index,
+                                  "mismatched function signatures: expected 'function test8(public string s, int i)'," +
+                                          " found 'function test8(string s, public int i)'", 84, 5);
+    }
+
+    @Test
+    public void testInvalidTypeReferenceAcrossModules() {
+        CompileResult result = BCompileUtil.compile("test-src/object/ObjectProject", "object_reference_negative");
+        int index = 0;
+
+        Assert.assertEquals(result.getErrorCount(), 3);
+        BAssertUtil.validateError(result, index++,
+                                  "incompatible type reference 'abc:Foo': a referenced object cannot have non-public " +
+                                          "fields or methods", 20, 6);
+        BAssertUtil.validateError(result, index++,
+                                  "incompatible type reference 'abc:Bar': a referenced object cannot have non-public " +
+                                          "fields or methods", 21, 6);
+        BAssertUtil.validateError(result, index,
+                                  "incompatible type reference 'abc:Baz': a referenced object cannot have non-public " +
+                                          "fields or methods", 22, 6);
     }
 }
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/balo/test_projects/test_project/src/foo/object_definitions.bal b/tests/jballerina-unit-test/src/test/resources/test-src/balo/test_projects/test_project/src/foo/object_definitions.bal
index ed3051b2c896..d3b2e563c834 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/balo/test_projects/test_project/src/foo/object_definitions.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/balo/test_projects/test_project/src/foo/object_definitions.bal
@@ -116,10 +116,10 @@ function passSelfAsValue(Boy p) returns string {
 }
 
 public type Bin abstract object {
-    public int age = 10;
-    public string name = "sample name";
-    public int year = 50;
-    public string month = "february";
+    public int age;
+    public string name;
+    public int year;
+    public string month;
 
     public function attachFunc1(int add, string value1) returns [int, string];
 
@@ -210,8 +210,8 @@ public type Architect object {
 };
 
 public type Country abstract object {
-    public int age = 10;
-    public string month = "february";
+    public int age;
+    public string month;
 
     public function attachInterface(int add) returns int;
 };
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/balo/test_projects/test_project/src/foo/object_type_reference.bal b/tests/jballerina-unit-test/src/test/resources/test-src/balo/test_projects/test_project/src/foo/object_type_reference.bal
index 4eb574602dc8..f44f60128d56 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/balo/test_projects/test_project/src/foo/object_type_reference.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/balo/test_projects/test_project/src/foo/object_type_reference.bal
@@ -15,8 +15,8 @@
 // under the License.
 
 public type Person1 abstract object {
-    public int age = 10;
-    public string name = "sample name";
+    public int age;
+    public string name;
 
     public function getName(string greeting = "Hi") returns string;
 };
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/jvm/object_negatives.bal b/tests/jballerina-unit-test/src/test/resources/test-src/jvm/object_negatives.bal
index 2c38c9107a9b..1944964bf2d8 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/jvm/object_negatives.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/jvm/object_negatives.bal
@@ -17,13 +17,13 @@
 import testorg/subtyping;
 
 type ObjWithPvtField abstract object {
-    string name = "";
-    private int ssn = 0;
+    string name;
+    private int ssn;
 };
 
 type ObjWithPvtMethod abstract object {
-    string name = "";
-    int ssn = 0;
+    string name;
+    int ssn;
 
     private function test();
 };
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/jvm/objects_subtyping.bal b/tests/jballerina-unit-test/src/test/resources/test-src/jvm/objects_subtyping.bal
index 920d8ab5f41a..cec9b950b7b2 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/jvm/objects_subtyping.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/jvm/objects_subtyping.bal
@@ -66,8 +66,8 @@ function testCastingRuntimeError() returns Person1 {
 }
 
 type AbstractPerson abstract object {
-    public string name = "";
-    public int age = 0;
+    public string name;
+    public int age;
 
     public function toString() returns string;
 };
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/object/ObjectProject/src/abstract_objects_with_non_public_symbols/main.bal b/tests/jballerina-unit-test/src/test/resources/test-src/object/ObjectProject/src/abstract_objects_with_non_public_symbols/main.bal
new file mode 100644
index 000000000000..c0444730e7d4
--- /dev/null
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/object/ObjectProject/src/abstract_objects_with_non_public_symbols/main.bal
@@ -0,0 +1,33 @@
+// Copyright (c) 2019 WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
+//
+// WSO2 Inc. licenses this file to you under the Apache License,
+// Version 2.0 (the "License"); you may not use this file except
+// in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+public type Foo abstract object {
+    int a;
+
+    function m();
+};
+
+public type Bar abstract object {
+    public int b;
+
+    function n();
+};
+
+public type Baz abstract object {
+    int c;
+
+    public function o();
+};
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/object/ObjectProject/src/object_reference_negative/main.bal b/tests/jballerina-unit-test/src/test/resources/test-src/object/ObjectProject/src/object_reference_negative/main.bal
new file mode 100644
index 000000000000..75b753f577c9
--- /dev/null
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/object/ObjectProject/src/object_reference_negative/main.bal
@@ -0,0 +1,23 @@
+// Copyright (c) 2019 WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
+//
+// WSO2 Inc. licenses this file to you under the Apache License,
+// Version 2.0 (the "License"); you may not use this file except
+// in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+import abstract_objects_with_non_public_symbols as abc;
+
+type Bar object {
+    *abc:Foo;
+    *abc:Bar;
+    *abc:Baz;
+};
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/object/abstract-object-negative.bal b/tests/jballerina-unit-test/src/test/resources/test-src/object/abstract-object-negative.bal
index 959ba5016fcf..7bef7351be39 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/object/abstract-object-negative.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/object/abstract-object-negative.bal
@@ -10,20 +10,20 @@ public function testInitAbstractObjectWithNew () {
 }
 
 type Person1 abstract object {
-    public int age = 0;
-    public string name = "";
+    public int age;
+    public string name;
 
-    int year = 0;
-    string month = "";
+    int year;
+    string month;
 };
 
 // Abstract object with constructor method
 type Person2 abstract object {
-    public int age = 0;
-    public string name = "";
+    public int age;
+    public string name;
 
-    int year = 50;
-    string month = "february";
+    int year;
+    string month;
 
     function __init () {
     }
@@ -42,21 +42,21 @@ type Person3 object {
 
 // Abstract object with method definition
 type Person4 abstract object {
-    public int age = 0;
-    public string name = "";
+    public int age;
+    public string name;
 
-    int year = 0;
-    string month = "";
+    int year;
+    string month;
 
     public function getName() returns string {
-        return self.name;
+        return "name";
     }
 };
 
 // Abstract object with private field
 type Person6 abstract object {
-    private int age = 0;
-    public string name = "";
+    private int age;
+    public string name;
 
     private function getName() returns string;
 };
@@ -77,3 +77,8 @@ type Bar object {
 type Person7 abstract object {
     public function getName() returns string = external;
 };
+
+// Abstract object with field with default value.
+type Baz abstract object {
+    string xyz = "xyz";
+};
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/object/abstract_object.bal b/tests/jballerina-unit-test/src/test/resources/test-src/object/abstract_object.bal
index 3d465df6e09a..cb89abe20755 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/object/abstract_object.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/object/abstract_object.bal
@@ -15,13 +15,13 @@
 // under the License.
 
 public type Address abstract object {
-    public string city = "";
+    public string city;
 
     public function getCity() returns string;
 };
 
 public type StudentAddress object {
-    public string city = "";
+    public string city;
 
     public function __init(string city){
         self.city = city;
@@ -33,7 +33,7 @@ public type StudentAddress object {
 };
 
 public type Employee object {
-    public string city = "";
+    public string city;
     public Address address;
 
     function __init(string city, Address address) {
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/object/object-type-reference-1-negative.bal b/tests/jballerina-unit-test/src/test/resources/test-src/object/object-type-reference-1-negative.bal
index 7bd187eadf3a..33b4732e954f 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/object/object-type-reference-1-negative.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/object/object-type-reference-1-negative.bal
@@ -15,8 +15,8 @@
 // under the License.
 
 type Person1 abstract object {
-    public int age = 10;
-    public string name = "sample name";
+    public int age;
+    public string name;
 };
 
 type Employee1 object {
@@ -33,11 +33,11 @@ type Manager1 object {
 };
 
 type EmployeeWithSalary abstract object {
-    public float salary = 0.0;
+    public float salary;
 };
 
 type AnotherEmployeeWithSalary abstract object {
-    public int salary = 0;
+    public int salary;
 };
 
 type ManagerWithTwoSalaries object {
@@ -77,8 +77,8 @@ type E abstract object {
 
 // Test errors for unimplemented methods
 type Person2 abstract object {
-    public int age = 10;
-    public string name = "sample name";
+    public int age;
+    public string name;
 
     // Unimplemented function at the nested referenced type.
     public function getName(string? title) returns string;
@@ -86,7 +86,7 @@ type Person2 abstract object {
 
 type Employee2 abstract object {
     *Person2;
-    public float salary = 0.0;
+    public float salary;
 
     // Unimplemented function at the referenced type.
     public function getSalary() returns float;
@@ -126,11 +126,11 @@ type ObjectWithRedeclaredFunction_2 abstract object {
 };
 
 type RedecalredFieldObject_1 abstract object {
-    int x = 0;
+    int x;
 };
 
 type RedecalredFieldObject_2 abstract object {
-    int x = 0;
+    int x;
     *RedecalredFieldObject_1;
 };
 
@@ -151,3 +151,30 @@ type Too object {
         self.s = s;
     }
 };
+
+type ObjWithSameFunc1 abstract object {
+    function abc();
+    function xyz(int i);
+};
+
+type ObjWithSameFunc2 abstract object {
+    function xyz(int i);
+    function def(string s) returns string;
+};
+
+type ObjWithRedeclaredFuncsViaRefs object {
+    *ObjWithSameFunc1;
+    *ObjWithSameFunc2;
+
+    function xyz(int i) {
+
+    }
+
+    function abc() {
+
+    }
+
+    function def(string s) returns string {
+        return s;
+    }
+};
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/object/object-type-reference-2-negative.bal b/tests/jballerina-unit-test/src/test/resources/test-src/object/object-type-reference-2-negative.bal
index 8a170545daf4..00ec9be9f51b 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/object/object-type-reference-2-negative.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/object/object-type-reference-2-negative.bal
@@ -21,8 +21,8 @@ type Foo object {
 };
 
 type Bar abstract object {
-    int x = 0;
-    string y = "";
+    int x;
+    string y;
 };
 
 type XXX object {
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/object/object-type-reference.bal b/tests/jballerina-unit-test/src/test/resources/test-src/object/object-type-reference.bal
index eae5624992cd..3004abc074cf 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/object/object-type-reference.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/object/object-type-reference.bal
@@ -15,14 +15,14 @@
 // under the License.
 
 type Person1 abstract object {
-    public int age = 10;
-    public string name = "sample name";
+    public int age;
+    public string name;
 
     public function getName() returns string;
 };
 
 type Employee1 abstract object {
-    public float salary = 0.0;
+    public float salary;
 
     public function getSalary() returns float; 
 };
@@ -102,7 +102,7 @@ type Manager3 object {
 };
 
 type Employee2 abstract object {
-    public float salary = 0.0;
+    public float salary;
     *Person1;
 
     public function getSalary() returns float; 
@@ -136,15 +136,15 @@ type Manager4 object {
 };
 
 type Employee3 abstract object {
-    public float salary = 0.0;
+    public float salary;
     *Person3;
 
     public function getBonus(float ratio, int months=12) returns float;
 };
 
 type Person3 abstract object {
-    public int age = 10;
-    public string name = "sample name";
+    public int age;
+    public string name;
 
     public function getName(string greeting = "Hi") returns string;
 };
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/object/object-with-interface.bal b/tests/jballerina-unit-test/src/test/resources/test-src/object/object-with-interface.bal
index fba1507634ae..a0b5dc454017 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/object/object-with-interface.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/object/object-with-interface.bal
@@ -6,11 +6,11 @@ public function testObjectWithInterface () returns [int, string, int, string] {
 
 
 type Person abstract object {
-    public int age = 10;
-    public string name = "sample name";
+    public int age;
+    public string name;
 
-    int year = 50;
-    string month = "february";
+    int year;
+    string month;
 
     function attachFunc1(int add, string value1) returns [int, string];
 
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/object/object_func_reference_neg.bal b/tests/jballerina-unit-test/src/test/resources/test-src/object/object_func_reference_neg.bal
index 982cfe9f922d..cc311c92f3ae 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/object/object_func_reference_neg.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/object/object_func_reference_neg.bal
@@ -42,6 +42,8 @@ public type Foo abstract object {
 
     function test7() returns Status;
 
+    function test8(public string s, int i);
+
 };
 
 public type FooImpl1 object {
@@ -77,4 +79,9 @@ public type FooImpl1 object {
     function test7(int x = 0) returns Status {
         return "ON";
     }
+
+    // param visibility modifier mismatch
+    function test8(string s, public int i) {
+
+    }
 };
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/object/object_initialize_interface_object.bal b/tests/jballerina-unit-test/src/test/resources/test-src/object/object_initialize_interface_object.bal
index 3015d14a402d..f5435106f3a5 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/object/object_initialize_interface_object.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/object/object_initialize_interface_object.bal
@@ -5,7 +5,7 @@ function test () returns int {
 }
 
 type Person abstract object {
-    public int age = 0;
+    public int age;
 
     function test(int a, string n) returns string;
 };
diff --git a/tests/jballerina-unit-test/src/test/resources/test-src/statements/arrays/arraysofarrays/arrays-of-arrays.bal b/tests/jballerina-unit-test/src/test/resources/test-src/statements/arrays/arraysofarrays/arrays-of-arrays.bal
index faafcb91d940..853efc126585 100644
--- a/tests/jballerina-unit-test/src/test/resources/test-src/statements/arrays/arraysofarrays/arrays-of-arrays.bal
+++ b/tests/jballerina-unit-test/src/test/resources/test-src/statements/arrays/arraysofarrays/arrays-of-arrays.bal
@@ -206,11 +206,11 @@ function testArrayUnion() returns [boolean[][], string[][]] {
 }
 
 type Foo1 abstract object {
-    string fooId1 = "";
+    string fooId1;
 };
 
 type Foo2 abstract object {
-    string fooId2 = "";
+    string fooId2;
 };
 
 type Bar object {