in javac-ast-extension/src/org/jetbrains/jps/javac/ast/JavacTreeRefScanner.java [377:380]
private static boolean isToStringImplicitCall(TypeElement strElement, TypeElement element, JavacReferenceCollectorListener.ReferenceCollector collector) {
TypeElement string = collector.getNameTable().getStringElement();
return strElement == string && element != string;
}