Fix XMP null error

CHANGELOG.md

@@ -34,6 +34,7 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - After assigning an entry to a group, the item count is now properly colored to reflect the new membership of the entry. [#3112](https://github.com/JabRef/jabref/issues/3112)
 - The group panel is now properly updated when switching between libraries (or when closing/opening one). [#3142](https://github.com/JabRef/jabref/issues/3142)
 - We fixed an error where the number of matched entries shown in the group pane was not updated correctly. [#4441](https://github.com/JabRef/jabref/issues/4441)
+- We fixed a "null" error when writing XMP metadata. [#5449](https://github.com/JabRef/jabref/issues/5449)
 - We fixed an issue where empty keywords lead to a strange display of automatic keyword groups. [#5333](https://github.com/JabRef/jabref/issues/5333)
 - We fixed an error where the default color of a new group was white instead of dark gray. [#4868](https://github.com/JabRef/jabref/issues/4868)
 - We fixed an issue where the first field in the entry editor got the focus while performing a different action (like searching). [#5084](https://github.com/JabRef/jabref/issues/5084)

src/main/java/org/jabref/logic/xmp/DublinCoreExtractor.java

@@ -347,13 +347,11 @@ private void fillCustomField(Field field, String value) {
     public void fillDublinCoreSchema() {
         // Query privacy filter settings
         boolean useXmpPrivacyFilter = xmpPreferences.isUseXMPPrivacyFilter();
-        // Fields for which not to write XMP data later on:
-        Set<Field> filters = new TreeSet<>(xmpPreferences.getXmpPrivacyFilter());
 
         Set<Entry<Field, String>> fieldValues = new TreeSet<>(Comparator.comparing(fieldStringEntry -> fieldStringEntry.getKey().getName()));
         fieldValues.addAll(bibEntry.getFieldMap().entrySet());
         for (Entry<Field, String> field : fieldValues) {
-            if (useXmpPrivacyFilter && filters.contains(field.getKey())) {
+            if (useXmpPrivacyFilter && xmpPreferences.getXmpPrivacyFilter().contains(field.getKey())) {
                 continue;
             }
 

src/main/java/org/jabref/logic/xmp/XmpPreferences.java

@@ -1,16 +1,16 @@
 package org.jabref.logic.xmp;
 
-import java.util.List;
+import java.util.Set;
 
 import org.jabref.model.entry.field.Field;
 
 public class XmpPreferences {
 
     private final boolean useXMPPrivacyFilter;
-    private final List<Field> xmpPrivacyFilter;
+    private final Set<Field> xmpPrivacyFilter;
     private final Character keywordSeparator;
 
-    public XmpPreferences(boolean useXMPPrivacyFilter, List<Field> xmpPrivacyFilter, Character keywordSeparator) {
+    public XmpPreferences(boolean useXMPPrivacyFilter, Set<Field> xmpPrivacyFilter, Character keywordSeparator) {
         this.useXMPPrivacyFilter = useXMPPrivacyFilter;
         this.xmpPrivacyFilter = xmpPrivacyFilter;
         this.keywordSeparator = keywordSeparator;
@@ -20,7 +20,7 @@ public boolean isUseXMPPrivacyFilter() {
         return useXMPPrivacyFilter;
     }
 
-    public List<Field> getXmpPrivacyFilter() {
+    public Set<Field> getXmpPrivacyFilter() {
         return xmpPrivacyFilter;
     }
 

src/main/java/org/jabref/logic/xmp/XmpUtilWriter.java

@@ -11,8 +11,6 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map.Entry;
-import java.util.Set;
-import java.util.TreeSet;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
@@ -249,40 +247,38 @@ private static void writeDocumentInformation(PDDocument document,
 
         // Query privacy filter settings
         boolean useXmpPrivacyFilter = xmpPreferences.isUseXMPPrivacyFilter();
-        // Fields for which not to write XMP data later on:
-        Set<Field> filters = new TreeSet<>(xmpPreferences.getXmpPrivacyFilter());
 
         // Set all the values including key and entryType
-        for (Entry<Field, String> field : resolvedEntry.getFieldMap().entrySet()) {
-            Field fieldName = field.getKey();
-            String fieldContent = field.getValue();
+        for (Entry<Field, String> fieldValuePair : resolvedEntry.getFieldMap().entrySet()) {
+            Field field = fieldValuePair.getKey();
+            String fieldContent = fieldValuePair.getValue();
 
-            if (useXmpPrivacyFilter && filters.contains(fieldName)) {
+            if (useXmpPrivacyFilter && xmpPreferences.getXmpPrivacyFilter().contains(field)) {
                 // erase field instead of adding it
-                if (StandardField.AUTHOR.equals(fieldName)) {
+                if (StandardField.AUTHOR.equals(field)) {
                     di.setAuthor(null);
-                } else if (StandardField.TITLE.equals(fieldName)) {
+                } else if (StandardField.TITLE.equals(field)) {
                     di.setTitle(null);
-                } else if (StandardField.KEYWORDS.equals(fieldName)) {
+                } else if (StandardField.KEYWORDS.equals(field)) {
                     di.setKeywords(null);
-                } else if (StandardField.ABSTRACT.equals(fieldName)) {
+                } else if (StandardField.ABSTRACT.equals(field)) {
                     di.setSubject(null);
                 } else {
-                    di.setCustomMetadataValue("bibtex/" + fieldName, null);
+                    di.setCustomMetadataValue("bibtex/" + field, null);
                 }
                 continue;
             }
 
-            if (StandardField.AUTHOR.equals(fieldName)) {
+            if (StandardField.AUTHOR.equals(field)) {
                 di.setAuthor(fieldContent);
-            } else if (StandardField.TITLE.equals(fieldName)) {
+            } else if (StandardField.TITLE.equals(field)) {
                 di.setTitle(fieldContent);
-            } else if (StandardField.KEYWORDS.equals(fieldName)) {
+            } else if (StandardField.KEYWORDS.equals(field)) {
                 di.setKeywords(fieldContent);
-            } else if (StandardField.ABSTRACT.equals(fieldName)) {
+            } else if (StandardField.ABSTRACT.equals(field)) {
                 di.setSubject(fieldContent);
             } else {
-                di.setCustomMetadataValue("bibtex/" + fieldName, fieldContent);
+                di.setCustomMetadataValue("bibtex/" + field, fieldContent);
             }
         }
         di.setCustomMetadataValue("bibtex/entrytype", resolvedEntry.getType().getDisplayName());

src/main/java/org/jabref/preferences/JabRefPreferences.java

@@ -1535,7 +1535,7 @@ public LayoutFormatterPreferences getLayoutFormatterPreferences(JournalAbbreviat
 
     @Override
     public XmpPreferences getXMPPreferences() {
-        return new XmpPreferences(getBoolean(USE_XMP_PRIVACY_FILTER), getStringList(XMP_PRIVACY_FILTERS).stream().map(FieldFactory::parseField).collect(Collectors.toList()),
+        return new XmpPreferences(getBoolean(USE_XMP_PRIVACY_FILTER), getStringList(XMP_PRIVACY_FILTERS).stream().map(FieldFactory::parseField).collect(Collectors.toSet()),
                                   getKeywordDelimiter());
     }
 

src/test/java/org/jabref/logic/exporter/XmpExporterTest.java

@@ -184,7 +184,7 @@ public void writeMultipleEntriesInDifferentFiles(@TempDir Path testFolder) throw
 
     @Test
     public void exportSingleEntryWithPrivacyFilter(@TempDir Path testFolder) throws Exception {
-        when(xmpPreferences.getXmpPrivacyFilter()).thenReturn(Collections.singletonList(StandardField.AUTHOR));
+        when(xmpPreferences.getXmpPrivacyFilter()).thenReturn(Collections.singleton(StandardField.AUTHOR));
         when(xmpPreferences.isUseXMPPrivacyFilter()).thenReturn(true);
 
         Path file = testFolder.resolve("ThisIsARandomlyNamedFile");