private static boolean isEqualsMethod(MethodInvocationTree syntaxNode) {
   if (syntaxNode.arguments().size() == 1) {
     ExpressionTree methodSelect = syntaxNode.methodSelect();
     if (methodSelect.is(Tree.Kind.MEMBER_SELECT)) {
       MemberSelectExpressionTree expression = (MemberSelectExpressionTree) methodSelect;
       if ("equals".equals(expression.identifier().name())
           && syntaxNode.symbol().isMethodSymbol()) {
         Symbol.MethodSymbol symbol = (Symbol.MethodSymbol) syntaxNode.symbol();
         return symbol.parameterTypes().get(0).is("java.lang.Object");
       }
     }
   }
   return false;
 }
 @Override
 public void visitIdentifier(IdentifierTree tree) {
   if (methodSymbol.equals(tree.symbol().owner())) {
     used.add(tree.symbol());
   }
   super.visitIdentifier(tree);
 }