Method reverences language level highlighting

java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/PsiMethodReferenceExpressionImpl.java

@@ -104,6 +104,16 @@ public class PsiMethodReferenceExpressionImpl extends PsiReferenceExpressionBase
     return element.getManager().areElementsEquivalent(element, resolve());
   }
 
+  @Override
+  public void accept(@NotNull final PsiElementVisitor visitor) {
+    if (visitor instanceof JavaElementVisitor) {
+      ((JavaElementVisitor)visitor).visitMethodReferenceExpression(this);
+    }
+    else {
+      visitor.visitElement(this);
+    }
+  }
+
   @Override
   public String toString() {
     return "PsiMethodReferenceExpression:" + getText();

java/java-psi-impl/src/messages/JavaErrorMessages.properties

@@ -353,4 +353,5 @@ feature.try.with.resources=Try-with-resources
 feature.binary.literals=Binary literals
 feature.underscores.in.literals=Underscores in literals
 feature.extension.methods=Extension methods
+feature.method.references=Method references
 insufficient.language.level={0} are not supported at this language level