Fix false-positive resolution ambiguity when using akka

com.typesafe.akka:akka-cluster-sharding_2.12:2.5
akka.cluster.sharding.ClusterSharding  has the following methods:

    public static ClusterSharding get(ActorSystem var0) {
        return ClusterSharding$.MODULE$.get(var0);
    }

    public static Extension get(ActorSystem var0) {
        return ClusterSharding$.MODULE$.get(var0);
    }

NB: ClusterSharding  <: Extension
None of these methods is synthetic or something, but javac allows
calls like ClusterSharding.get(null)  and they get resolved
to the first method returning ClusterSharding

It seems that both javac and IntelliJ resolution algorithms filter out
such clashing declarations choosing the one that has the most
specific return type, the same idea is applied in the change

 #KT-17560 Fixed

compiler/testData/diagnostics/tests/j+k/selectMoreSpecific.kt

@@ -0,0 +1,16 @@
+// !CHECK_TYPE
+// FILE: A.java
+public class A {
+    public String foo() {}
+    public CharSequence foo() {}
+
+    public static String bar() {}
+    public static CharSequence bar() {}
+}
+
+// FILE: main.kt
+
+fun foo(a: A) {
+    a.foo() checkType { _<String>() }
+    A.bar() checkType { _<String>() }
+}

compiler/testData/diagnostics/tests/j+k/selectMoreSpecific.txt

@@ -0,0 +1,14 @@
+package
+
+public fun foo(/*0*/ a: A): kotlin.Unit
+
+public open class A {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open fun foo(): kotlin.String!
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    // Static members
+    public open fun bar(): kotlin.String!
+}

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -12100,6 +12100,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("selectMoreSpecific.kt")
+            public void testSelectMoreSpecific() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/j+k/selectMoreSpecific.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("serializable.kt")
             public void testSerializable() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/j+k/serializable.kt");

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/lazy/descriptors/LazyJavaScope.kt

@@ -36,6 +36,7 @@ import org.jetbrains.kotlin.load.java.structure.JavaValueParameter
 import org.jetbrains.kotlin.load.java.typeEnhancement.enhanceSignatures
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.DescriptorUtils
+import org.jetbrains.kotlin.resolve.retainMostSpecificInEachOverridableGroup
 import org.jetbrains.kotlin.resolve.scopes.DescriptorKindExclude.NonExtensions
 import org.jetbrains.kotlin.resolve.scopes.DescriptorKindFilter
 import org.jetbrains.kotlin.resolve.scopes.MemberScope
@@ -86,6 +87,8 @@ abstract class LazyJavaScope(protected val c: LazyJavaResolverContext) : MemberS
             }
         }
 
+        result.retainMostSpecificInEachOverridableGroup()
+
         computeNonDeclaredFunctions(result, name)
 
         enhanceSignatures(result).toList()

core/descriptors/src/org/jetbrains/kotlin/resolve/overridingUtils.kt

@@ -81,3 +81,9 @@ fun <H : Any> Collection<H>.selectMostSpecificInEachOverridableGroup(
     }
     return result
 }
+
+fun <D : CallableDescriptor> MutableCollection<D>.retainMostSpecificInEachOverridableGroup() {
+    val newResult = selectMostSpecificInEachOverridableGroup { this }
+    if (size == newResult.size) return
+    retainAll(newResult)
+}