extract method: allow to choose return type from hierarchy (IDEA-79995)

java/java-tests/testData/refactoring/extractMethod/ChangedReturnType.java

@@ -0,0 +1,13 @@
+class X {
+  void foo(java.util.List l) {
+    for (Object o : l) {
+      <selection>if (o == null) continue;
+      String x = bar(o);</selection>
+      System.out.println(x);
+    }
+  }
+
+  private String bar(Object o) {
+    return "";
+  }
+}

java/java-tests/testData/refactoring/extractMethod/ChangedReturnType_after.java

@@ -0,0 +1,22 @@
+import org.jetbrains.annotations.Nullable;
+
+class X {
+  void foo(java.util.List l) {
+    for (Object o : l) {
+        Object x = newMethod(o);
+        if (x == null) continue;
+      System.out.println(x);
+    }
+  }
+
+    @Nullable
+    private Object newMethod(Object o) {
+        if (o == null) return null;
+        String x = bar(o);
+        return x;
+    }
+
+    private String bar(Object o) {
+    return "";
+  }
+}