Release original Java descriptors while enhancing

It's both more correct and helps to release memory retained by
descriptor before enhancement

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/descriptors/JavaConstructorDescriptor.java

@@ -91,14 +91,26 @@ public class JavaConstructorDescriptor extends ConstructorDescriptorImpl impleme
 
         assert newName == null : "Attempt to rename constructor: " + this;
 
-        JavaConstructorDescriptor result = new JavaConstructorDescriptor(
-                (ClassDescriptor) newOwner, this, getAnnotations(), isPrimary, kind, getSourceToUseForCopy(preserveSource, original)
-        );
+        JavaConstructorDescriptor result = createDescriptor((ClassDescriptor) newOwner, (JavaConstructorDescriptor) original, kind,
+                                                            getSourceToUseForCopy(preserveSource, original));
         result.setHasStableParameterNames(hasStableParameterNames());
         result.setHasSynthesizedParameterNames(hasSynthesizedParameterNames());
         return result;
     }
 
+    @NotNull
+    protected JavaConstructorDescriptor createDescriptor(
+            @NotNull ClassDescriptor newOwner,
+            @Nullable JavaConstructorDescriptor original,
+            @NotNull Kind kind,
+            @NotNull SourceElement sourceElement
+    ) {
+        return new JavaConstructorDescriptor(
+                newOwner, original, getAnnotations(), isPrimary, kind,
+                sourceElement
+        );
+    }
+
     @Override
     @NotNull
     public JavaConstructorDescriptor enhance(
@@ -106,7 +118,7 @@ public class JavaConstructorDescriptor extends ConstructorDescriptorImpl impleme
             @NotNull List<KotlinType> enhancedValueParametersTypes,
             @NotNull KotlinType enhancedReturnType
     ) {
-        JavaConstructorDescriptor enhanced = createSubstitutedCopy(getContainingDeclaration(), getOriginal(), getKind(), null, false);
+        JavaConstructorDescriptor enhanced = createSubstitutedCopy(getContainingDeclaration(), /* original = */ null, getKind(), null, false);
         // We do not use doSubstitute here as in JavaMethodDescriptor.enhance because type parameters of constructor belongs to class
         enhanced.initialize(
                 enhancedReceiverType,

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/descriptors/JavaMethodDescriptor.java

@@ -138,15 +138,13 @@ public class JavaMethodDescriptor extends SimpleFunctionDescriptorImpl implement
         List<ValueParameterDescriptor> enhancedValueParameters =
                 UtilKt.copyValueParameters(enhancedValueParametersTypes, getValueParameters(), this);
 
-        // We use `doSubstitute` here because it does exactly what we need:
-        // 1. creates full copy of descriptor
-        // 2. copies method's type parameters (with new containing declaration) and properly substitute to them in value parameters, return type and etc.
         JavaMethodDescriptor enhancedMethod =
                 (JavaMethodDescriptor) newCopyBuilder()
                         .setValueParameters(enhancedValueParameters)
                         .setReturnType(enhancedReturnType)
                         .setExtensionReceiverType(enhancedReceiverType)
-                        .setOriginal(getOriginal())
+                        .setDropOriginalInContainingParts()
+                        .setPreserveSourceElement()
                         .build();
 
         assert enhancedMethod != null : "null after substitution while enhancing " + toString();

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/typeEnhancement/signatureEnhancement.kt

@@ -26,7 +26,7 @@ fun <D : CallableMemberDescriptor> enhanceSignatures(platformSignatures: Collect
     }
 }
 
-fun <D : CallableMemberDescriptor> D.enhanceSignature(): D {
+private fun <D : CallableMemberDescriptor> D.enhanceSignature(): D {
     // TODO type parameters
     // TODO use new type parameters while enhancing other types
     // TODO Propagation into generic type arguments