[Bug #51] Fix the issue of attempting to add JSON-LD context to a collection node.

Author: ledsoft

src/main/java/cz/cvut/kbss/jsonld/serialization/JsonLdTreeBuilder.java

@@ -85,6 +85,10 @@ public void closeObject(SerializationContext<?> ctx) {
         if (!ctx.isCurrentEmpty()) {
             currentNode.prependItem(ctx.getContextNode());
         }
+        closeCurrentNode();
+    }
+
+    private void closeCurrentNode() {
         currentNode.close();
         if (!nodeStack.empty()) {
             this.currentNode = nodeStack.pop();
@@ -126,7 +130,7 @@ public void openCollection(SerializationContext<? extends Collection<?>> ctx) {
     @Override
     public void closeCollection(SerializationContext<?> ctx) {
         assert currentNode instanceof CollectionNode;
-        closeObject(ctx);
+        closeCurrentNode();
     }
 
     public CompositeNode<?> getTreeRoot() {

src/test/java/cz/cvut/kbss/jsonld/serialization/JsonLdTreeBuilderTest.java

@@ -23,7 +23,6 @@
 import cz.cvut.kbss.jsonld.environment.Vocabulary;
 import cz.cvut.kbss.jsonld.environment.model.*;
 import cz.cvut.kbss.jsonld.serialization.context.DummyJsonLdContext;
-import cz.cvut.kbss.jsonld.serialization.context.MappingJsonLdContextFactory;
 import cz.cvut.kbss.jsonld.serialization.model.*;
 import cz.cvut.kbss.jsonld.serialization.serializer.LiteralValueSerializers;
 import cz.cvut.kbss.jsonld.serialization.serializer.compact.DefaultValueSerializer;