Checking for return type in kotlin signature if have super methods.

compiler/testData/loadJava/kotlinSignature/propagation/return/CantMakeImmutableInSubclass.java

@@ -0,0 +1,21 @@
+package test;
+
+import org.jetbrains.annotations.NotNull;
+import java.util.*;
+
+import jet.runtime.typeinfo.KotlinSignature;
+import org.jetbrains.jet.jvm.compiler.annotation.ExpectLoadError;
+
+public interface CantMakeImmutableInSubclass {
+
+    public interface Super {
+        @KotlinSignature("fun foo(): MutableCollection<String>")
+        Collection<String> foo();
+    }
+
+    public interface Sub extends Super {
+        @ExpectLoadError("Return type is changed to not subtype for method which overrides another: List<String>, was: MutableList<String>")
+        @KotlinSignature("fun foo(): List<String>")
+        List<String> foo();
+    }
+}

compiler/testData/loadJava/kotlinSignature/propagation/return/CantMakeImmutableInSubclass.kt

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+package test
+
+public trait CantMakeImmutableInSubclass: Object {
+
+    public trait Super: Object {
+        public fun foo(): MutableCollection<String>
+    }
+
+    public trait Sub: Super {
+        override fun foo(): MutableList<String>
+    }
+}

compiler/testData/loadJava/kotlinSignature/propagation/return/CantMakeImmutableInSubclass.txt

@@ -0,0 +1,10 @@
+namespace test
+
+public abstract trait test.CantMakeImmutableInSubclass : java.lang.Object {
+    public abstract trait test.CantMakeImmutableInSubclass.Sub : test.CantMakeImmutableInSubclass.Super {
+        public abstract override /*1*/ fun foo(): jet.MutableList<jet.String>
+    }
+    public abstract trait test.CantMakeImmutableInSubclass.Super : java.lang.Object {
+        public abstract fun foo(): jet.MutableCollection<jet.String>
+    }
+}