diff --git a/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java
index b23a6a3..f2c704b 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/CodeGenerator.java
@@ -1046,7 +1046,7 @@
 								// to get a descendant resource directly. (e.g, .todos.{year}.{month}.{day}.{id} ==> .getTodos().getTodo(year, month, day, id))
 								if (doesChainInvocations) {
 									Term newGetter = new Term(new Symbol(getterPrefix + typeName, -1, Symbol.Type.METHOD));
-									newGetter.addChild(getter);
+									if (getter != null) newGetter.addChild(getter);
 									getter = newGetter;
 									doesChainInvocations = false;
 								}
@@ -1165,7 +1165,7 @@
 									// to get a descendant resource directly. (e.g, .todos.{year}.{month}.{day}.{id} ==> .getTodos().getTodo(year, month, day, id))
 									if (doesChainInvocations) {
 										Term newGetter = new Term(new Symbol(getterPrefix + typeName, -1, Symbol.Type.METHOD));
-										newGetter.addChild(getter);
+										if (getter != null) newGetter.addChild(getter);
 										getter = newGetter;
 										doesChainInvocations = false;
 									}
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java b/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java
index 08fd9c0..f3d9070 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/CodeGeneratorFromDataFlowGraph.java
@@ -1077,7 +1077,7 @@
 								Type srcResType2 = src2.getResourceStateType();
 								String srcResName2 = langSpec.toVariableName(getComponentName(src2.getResourceHierarchy(), langSpec));
 								if (platformSpec.isMonolithic()) {
-									String srcGetter = getPullAccessor(platformSpec).getDirectStateAccessorFor(src2, resourceNode.getInSideResource(curChannel)).toImplementation(new String[] {});
+									String srcGetter = getPullAccessor(platformSpec).getDirectStateAccessorFor(src2, resourceNode.getInSideResource(curChannel)).toImplementation(new String[] {""});
 									stateGetter.addStatement(langSpec.getVariableDeclaration(srcResType2.getInterfaceTypeName(), srcResName2) 
 											+ langSpec.getAssignment() + srcGetter + langSpec.getStatementDelimiter());
 								} else {
@@ -1094,7 +1094,7 @@
 									Type srcResType2 = src2.getResourceStateType();
 									String srcResName2 = langSpec.toVariableName(getComponentName(src2.getResourceHierarchy(), langSpec));
 									if (platformSpec.isMonolithic()) {
-										String dependingGetter = getPullAccessor(platformSpec).getDirectStateAccessorFor(src2, resourceNode.getInSideResource(curChannel)).toImplementation(new String[] {});
+										String dependingGetter = getPullAccessor(platformSpec).getDirectStateAccessorFor(src2, resourceNode.getInSideResource(curChannel)).toImplementation(new String[] {""});
 										stateGetter.addStatement(langSpec.getVariableDeclaration(srcResType2.getInterfaceTypeName(), srcResName2)
 												+ langSpec.getAssignment() + dependingGetter + langSpec.getStatementDelimiter());
 									} else {
@@ -1181,9 +1181,9 @@
 										Expression parentGetter = getPullAccessor(platformSpec).getDirectStateAccessorFor(insideResPath, dstResPath);
 										Term valueGetter = new Term(new Symbol(getterOfResourceState, 1, Symbol.Type.METHOD));
 										valueGetter.addChild(parentGetter);
-										parent = valueGetter.toImplementation(new String[] {});
+										parent = valueGetter.toImplementation(new String[] {""});
 									} else {
-										parent = getPullAccessor(platformSpec).getDirectStateAccessorFor(insideResPath, dstResPath).toImplementation(new String[] {});
+										parent = getPullAccessor(platformSpec).getDirectStateAccessorFor(insideResPath, dstResPath).toImplementation(new String[] {""});
 									}
 								} else {
 									// for REST API
@@ -1507,7 +1507,7 @@
 								paramConverter += langSpec.getClosingScoreDelimiter();
 								((RestApiSpecific) platformSpec).addJsonException(update);
 							}
-							if (paramConverter.length() > 0 && !update.getBody().getStatements().contains(paramConverter)) {
+							if (paramConverter.length() > 0 && (update.getBody() == null || !update.getBody().getStatements().contains(paramConverter))) {
 								update.addFirstStatement(paramConverter);
 							}
 						}
@@ -1864,9 +1864,9 @@
 														Expression getter = getPullAccessor(platformSpec).getDirectStateAccessorFor(insideResPath, resourceNode.getOutSideResource(directDstCh));
 														Term valueGetter = new Term(new Symbol(getterOfResourceState, 1, Symbol.Type.METHOD));
 														valueGetter.addChild(getter);
-														parent = valueGetter.toImplementation(new String[] {});
+														parent = valueGetter.toImplementation(new String[] {""});
 													} else {
-														parent = getPullAccessor(platformSpec).getDirectStateAccessorFor(insideResPath, resourceNode.getOutSideResource(directDstCh)).toImplementation(new String[] {});
+														parent = getPullAccessor(platformSpec).getDirectStateAccessorFor(insideResPath, resourceNode.getOutSideResource(directDstCh)).toImplementation(new String[] {""});
 													}
 												} else {
 													// for REST API
@@ -2787,9 +2787,9 @@
 															Expression getter = getPullAccessor(platformSpec).getDirectStateAccessorFor(insideResPath, resourceNode.getOutSideResource(directDstCh));
 															Term valueGetter = new Term(new Symbol(getterOfResourceState, 1, Symbol.Type.METHOD));
 															valueGetter.addChild(getter);
-															parent = valueGetter.toImplementation(new String[] {});
+															parent = valueGetter.toImplementation(new String[] {""});
 														} else {
-															parent = getPullAccessor(platformSpec).getDirectStateAccessorFor(insideResPath, resourceNode.getOutSideResource(directDstCh)).toImplementation(new String[] {});
+															parent = getPullAccessor(platformSpec).getDirectStateAccessorFor(insideResPath, resourceNode.getOutSideResource(directDstCh)).toImplementation(new String[] {""});
 														}
 													} else {
 														// for REST API
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/JavaMethodBodyGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/JavaMethodBodyGenerator.java
index f220abd..7d89968 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/JavaMethodBodyGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/JavaMethodBodyGenerator.java
@@ -496,7 +496,7 @@
 													}
 													insideResPath = insideResPath.getParent();
 													if (insideResPath != null) {
-														String parent = JavaCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, src.getOutSideResource(directDstCh)).toImplementation(new String[] {});
+														String parent = JavaCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, src.getOutSideResource(directDstCh)).toImplementation(new String[] {""});
 														if (selType.equals(DataConstraintModel.typeInt)) {
 															// make a for loop (for a list) for broadcasting.
 															srcUpdate.addFirstStatement("for (int " + forVarName + " = 0; " + forVarName +" < " + parent + ".size(); " + forVarName + "++) {");
@@ -657,7 +657,7 @@
 													}
 													insideResPath = insideResPath.getParent();
 													if (insideResPath != null) {
-														String parent = JavaCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, src.getOutSideResource(directDstCh)).toImplementation(new String[] {});
+														String parent = JavaCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, src.getOutSideResource(directDstCh)).toImplementation(new String[] {""});
 														if (selType.equals(DataConstraintModel.typeInt)) {
 															// make a for loop (for a list) for broadcasting.
 															srcInput.addFirstStatement("for (int " + varName + " = 0; " + varName +" < " + parent + ".size(); " + varName + "++) {");
@@ -747,7 +747,7 @@
 															ResourcePath src2 = cm2.getResource();
 															Type srcResType2 = src2.getResourceStateType();
 															String srcResName2 = JerseyCodeGenerator.toVariableName(JerseyCodeGenerator.getComponentName(src2.getResourceHierarchy()));
-															String srcGetter = JavaCodeGenerator.pullAccessor.getDirectStateAccessorFor(src2, dst.getInSideResource(curChannel)).toImplementation(new String[] {});
+															String srcGetter = JavaCodeGenerator.pullAccessor.getDirectStateAccessorFor(src2, dst.getInSideResource(curChannel)).toImplementation(new String[] {""});
 															getter.addStatement(srcResType2.getInterfaceTypeName() + " " + srcResName2 + " = " + srcGetter + ";");
 														} else {
 															// a depending channel member.
@@ -757,7 +757,7 @@
 																// generate a pull data transfer from a depending in/ref resource.
 																Type srcResType2 = src2.getResourceStateType();
 																String srcResName2 = JerseyCodeGenerator.toVariableName(JerseyCodeGenerator.getComponentName(src2.getResourceHierarchy()));
-																String dependingGetter = JavaCodeGenerator.pullAccessor.getDirectStateAccessorFor(src2, dst.getInSideResource(curChannel)).toImplementation(new String[] {});
+																String dependingGetter = JavaCodeGenerator.pullAccessor.getDirectStateAccessorFor(src2, dst.getInSideResource(curChannel)).toImplementation(new String[] {""});
 																getter.addStatement(srcResType2.getInterfaceTypeName() + " " + srcResName2 + " = " + dependingGetter + ";");
 															}
 														}
@@ -830,7 +830,7 @@
 														}
 														insideResPath = insideResPath.getParent();
 														if (insideResPath != null) {
-															String parent = JavaCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, dst.getInSideResource(ch)).toImplementation(new String[] {});
+															String parent = JavaCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, dst.getInSideResource(ch)).toImplementation(new String[] {""});
 															if (selType.equals(DataConstraintModel.typeInt)) {
 																// make a for loop (for a list) for data collecting.
 																getter.addFirstStatement("for (int " + varName + " = 0; " + varName +" < " + parent + ".size(); " + varName + "++) {");
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/JavaSpecific.java b/AlgebraicDataflowArchitectureModel/src/generators/JavaSpecific.java
index 58357f2..7115e57 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/JavaSpecific.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/JavaSpecific.java
@@ -193,7 +193,7 @@
 
 	@Override
 	public String getIfStatement(Term condition, String block) {
-		return "if (" + condition.toImplementation(new String[] {})+ ") {\n" + "\t" + block.replace("\n", "\n\t") + "\n}";
+		return "if (" + condition.toImplementation(new String[] {""})+ ") {\n" + "\t" + block.replace("\n", "\n\t") + "\n}";
 	}
 
 	@Override
diff --git a/AlgebraicDataflowArchitectureModel/src/generators/JerseyMethodBodyGenerator.java b/AlgebraicDataflowArchitectureModel/src/generators/JerseyMethodBodyGenerator.java
index fdfd502..abd1e02 100644
--- a/AlgebraicDataflowArchitectureModel/src/generators/JerseyMethodBodyGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/generators/JerseyMethodBodyGenerator.java
@@ -406,7 +406,7 @@
 												paramConverter += "}";
 												update.addThrow("JsonProcessingException");
 											}
-											if (paramConverter.length() > 0 && !update.getBody().getStatements().contains(paramConverter)) {
+											if (paramConverter.length() > 0 && (update.getBody() == null || !update.getBody().getStatements().contains(paramConverter))) {
 												update.addFirstStatement(paramConverter);
 											}
 										}
@@ -590,9 +590,9 @@
 																Expression getter = JerseyCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, src.getPrimaryResourcePath());
 																Term valueGetter = new Term(new Symbol("getValue", 1, Symbol.Type.METHOD));
 																valueGetter.addChild(getter);
-																parent = valueGetter.toImplementation(new String[] {});
+																parent = valueGetter.toImplementation(new String[] {""});
 															} else {
-																parent = JerseyCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, src.getPrimaryResourcePath()).toImplementation(new String[] {});
+																parent = JerseyCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, src.getPrimaryResourcePath()).toImplementation(new String[] {""});
 															}
 															if (insideResPath != null) {
 																if (selType.equals(DataConstraintModel.typeInt)) {
@@ -773,9 +773,9 @@
 															Expression getter = JerseyCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, src.getPrimaryResourcePath());
 															Term valueGetter = new Term(new Symbol("getValue", 1, Symbol.Type.METHOD));
 															valueGetter.addChild(getter);
-															parent = valueGetter.toImplementation(new String[] {});
+															parent = valueGetter.toImplementation(new String[] {""});
 														} else {
-															parent = JerseyCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, src.getPrimaryResourcePath()).toImplementation(new String[] {});
+															parent = JerseyCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, src.getPrimaryResourcePath()).toImplementation(new String[] {""});
 														}
 														if (insideResPath != null) {
 															if (selType.equals(DataConstraintModel.typeInt)) {
@@ -999,9 +999,9 @@
 																	Expression parentGetter = JerseyCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, dst.getInSideResource(ch));
 																	Term valueGetter = new Term(new Symbol("getValue", 1, Symbol.Type.METHOD));
 																	valueGetter.addChild(parentGetter);
-																	parent = valueGetter.toImplementation(new String[] {});
+																	parent = valueGetter.toImplementation(new String[] {""});
 																} else {
-																	parent = JerseyCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, dst.getInSideResource(ch)).toImplementation(new String[] {});
+																	parent = JerseyCodeGenerator.pullAccessor.getDirectStateAccessorFor(insideResPath, dst.getInSideResource(ch)).toImplementation(new String[] {""});
 																}
 															} else {
 																parent = JerseyCodeGenerator.toVariableName(JerseyCodeGenerator.getComponentName(insideResPath.getResourceHierarchy()));