Introduce JetParameter#hasDefaultValue() and use it instead of getDefaultValue() where appropriate

compiler/frontend/src/org/jetbrains/jet/lang/psi/JetParameter.java

@@ -45,6 +45,14 @@ public class JetParameter extends JetNamedDeclarationStub<PsiJetParameterStub> {
         return getStubOrPsiChild(JetStubElementTypes.TYPE_REFERENCE);
     }
 
+    public boolean hasDefaultValue() {
+        PsiJetParameterStub stub = getStub();
+        if (stub != null) {
+            return stub.hasDefaultValue();
+        }
+        return getDefaultValue() != null;
+    }
+
     @Nullable
     public JetExpression getDefaultValue() {
         PsiJetParameterStub stub = getStub();

compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetParameterElementType.java

@@ -40,7 +40,7 @@ public class JetParameterElementType extends JetStubElementType<PsiJetParameterS
     public PsiJetParameterStub createStub(@NotNull JetParameter psi, StubElement parentStub) {
         return new PsiJetParameterStubImpl(parentStub, psi.getFqName(), StringRef.fromString(psi.getName()),
                                            psi.isMutable(), psi.isVarArg(), psi.hasValOrVarNode(),
-                                           psi.getDefaultValue() != null);
+                                           psi.hasDefaultValue());
     }
 
     @Override

compiler/frontend/src/org/jetbrains/jet/lang/resolve/DescriptorResolver.java

@@ -556,7 +556,7 @@ public class DescriptorResolver {
                 annotations,
                 JetPsiUtil.safeName(valueParameter.getName()),
                 variableType,
-                valueParameter.getDefaultValue() != null,
+                valueParameter.hasDefaultValue(),
                 varargElementType
         );
 
@@ -1151,9 +1151,8 @@ public class DescriptorResolver {
             if (parameter != null) {
 
                 // This check is redundant: the parser does not allow a default value, but we'll keep it just in case
-                JetExpression defaultValue = parameter.getDefaultValue();
-                if (defaultValue != null) {
-                    trace.report(SETTER_PARAMETER_WITH_DEFAULT_VALUE.on(defaultValue));
+                if (parameter.hasDefaultValue()) {
+                    trace.report(SETTER_PARAMETER_WITH_DEFAULT_VALUE.on(parameter.getDefaultValue()));
                 }
 
                 JetType type;