Start wrok on #3394, allow @JsonAnySetter on JsonNode valued field

src/main/java/com/fasterxml/jackson/databind/introspect/BasicBeanDescription.java

@@ -322,9 +322,10 @@ public AnnotatedMember findAnySetterAccessor() throws IllegalArgumentException
                 // For now let's require a Map; in future can add support for other
                 // types like perhaps Iterable<Map.Entry>?
                 Class<?> type = anyField.getRawType();
-                if (!Map.class.isAssignableFrom(type)) {
+                if (!Map.class.isAssignableFrom(type)
+                        && !JsonNode.class.isAssignableFrom(type)) {
                     throw new IllegalArgumentException(String.format(
-"Invalid 'any-setter' annotation on field '%s': type is not instance of java.util.Map",
+"Invalid 'any-setter' annotation on field '%s': type is not instance of `java.util.Map` or `JsonNode`",
 anyField.getName()));
                 }
                 return anyField;

src/test/java/com/fasterxml/jackson/databind/deser/AnySetter3394Test.java

@@ -0,0 +1,29 @@
+package com.fasterxml.jackson.databind.deser;
+
+import com.fasterxml.jackson.annotation.JsonAnySetter;
+
+import com.fasterxml.jackson.databind.*;
+
+// for [databind#3394]
+public class AnySetter3394Test extends BaseMapTest
+{
+    static class AnySetter3394Bean {
+        @JsonAnySetter
+        public JsonNode extraData;
+    }
+
+    /*
+    /**********************************************************
+    /* Test methods
+    /**********************************************************
+     */
+
+    private final ObjectMapper MAPPER = newJsonMapper();
+
+    public void testAnySetterWithJsonNode() throws Exception
+    {
+        final String DOC = a2q("{'test': 3}");
+        AnySetter3394Bean bean = MAPPER.readValue(DOC, AnySetter3394Bean.class);
+        assertEquals(DOC, ""+bean.extraData);
+    }
+}