Some tests for override action has been added.

idea/testData/codeInsight/overrideImplement/complexMultiOverride.kt

@@ -0,0 +1,9 @@
+open class Base<A, B, C>() {
+    open val method : (A?) -> A = { it!! }
+    open fun foo(value : B) : B = value
+    open fun bar(value : () -> C) : (String) -> C = { value() }
+}
+
+class C : Base<String, C, Unit>() {
+    <caret>
+}