Java: Avoid duplicates for shadowed members in completion list for arguments of reflection calls. Simplify building the list of method names with PsiClass.getVisibleSignatures() (IDEA-167250)

java/java-tests/testData/codeInsight/completion/reflectionOverload/ShadowedMethod.java

@@ -0,0 +1,13 @@
+class Main {
+  void foo() {
+    Test.class.getMethod("<caret>");
+  }
+}
+
+class Test extends Parent {
+  public static void shadowed(){}
+}
+
+class Parent {
+  public static void shadowed(){}
+}