functional interface suggester: check return types and try to infer

java/java-tests/testData/refactoring/introduceFunctionalParameter/afterFunction.java

@@ -0,0 +1,20 @@
+import java.util.function.Supplier;
+
+class Test {
+  void bar() {
+    foo(new Supplier<String>() {
+        public String get() {
+            String s = "";
+            System.out.println(s);
+            return s;
+        }
+    });
+  }
+
+  void foo(Supplier<String> anObject) {
+
+      String s = anObject.get();
+
+      System.out.println(s);
+  }
+}