KT-10939 CANNOT_COMPLETE_RESOLVE for inherited generic interface method

'original' for value parameters of fake override is not a value parameter of unsubstituted fake override.
Match value parameters by index.

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/results/CandidateCallWithArgumentMapping.kt

@@ -69,6 +69,7 @@ class CandidateCallWithArgumentMapping<D : CallableDescriptor, K> private constr
             val argumentsToParameters = hashMapOf<K, ValueParameterDescriptor>()
             var parametersWithDefaultValuesCount = 0
 
+            val unsubstitutedValueParameters = call.candidateDescriptor.original.valueParameters
             for ((valueParameterDescriptor, resolvedValueArgument) in call.unsubstitutedValueArguments.entries) {
                 if (resolvedValueArgument is DefaultValueArgument) {
                     parametersWithDefaultValuesCount++
@@ -76,7 +77,10 @@ class CandidateCallWithArgumentMapping<D : CallableDescriptor, K> private constr
                 else {
                     val keys = resolvedArgumentToKeys(resolvedValueArgument)
                     for (argumentKey in keys) {
-                        argumentsToParameters[argumentKey] = valueParameterDescriptor.original
+                        // TODO fix 'original' for value parameters of Java generic descriptors.
+                        // Should be able to use just 'valueParameterDescriptor' below.
+                        // Doesn't work for Java generic descriptors. See also KT-10939.
+                        argumentsToParameters[argumentKey] = unsubstitutedValueParameters[valueParameterDescriptor.index]
                     }
                 }
             }

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/results/OverloadingConflictResolver.kt

@@ -326,9 +326,6 @@ class OverloadingConflictResolver(private val builtIns: KotlinBuiltIns) {
     private fun getVarargElementTypeOrType(parameterDescriptor: ValueParameterDescriptor): KotlinType =
             parameterDescriptor.varargElementType ?: parameterDescriptor.type
 
-    private val CallableDescriptor.hasVarargs: Boolean get() =
-            this.valueParameters.any { it.varargElementType != null }
-
     private fun typeNotLessSpecific(specific: KotlinType, general: KotlinType): Boolean {
         val isSubtype = KotlinTypeChecker.DEFAULT.isSubtypeOf(specific, general) || numericTypeMoreSpecific(specific, general)