[FIR] Copy java enum entry during enhancement instead of mutating it

#KT-57949 Fixed

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/enhancement/SignatureEnhancement.kt

@@ -109,10 +109,14 @@ class FirSignatureEnhancement(
                     )
 
                 val newReturnTypeRef = enhanceReturnType(firElement, emptyList(), firElement.computeDefaultQualifiers(), predefinedInfo)
-                return firElement.symbol.apply {
-                    this.fir.replaceReturnTypeRef(newReturnTypeRef)
-                    session.lookupTracker?.recordTypeResolveAsLookup(newReturnTypeRef, this.fir.source, null)
-                }
+
+                return buildEnumEntryCopy(firElement) {
+                    symbol = FirEnumEntrySymbol(firElement.symbol.callableId)
+                    returnTypeRef = newReturnTypeRef
+                    origin = FirDeclarationOrigin.Enhancement
+                }.apply {
+                    session.lookupTracker?.recordTypeResolveAsLookup(newReturnTypeRef, this.source, null)
+                }.symbol
             }
             is FirField -> {
                 if (firElement.returnTypeRef !is FirJavaTypeRef) return original

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/declarations/builder/FirEnumEntryBuilder.kt

@@ -77,3 +77,29 @@ inline fun buildEnumEntry(init: FirEnumEntryBuilder.() -> Unit): FirEnumEntry {
     }
     return FirEnumEntryBuilder().apply(init).build()
 }
+
+@OptIn(ExperimentalContracts::class)
+inline fun buildEnumEntryCopy(original: FirEnumEntry, init: FirEnumEntryBuilder.() -> Unit): FirEnumEntry {
+    contract {
+        callsInPlace(init, kotlin.contracts.InvocationKind.EXACTLY_ONCE)
+    }
+    val copyBuilder = FirEnumEntryBuilder()
+    copyBuilder.source = original.source
+    copyBuilder.resolvePhase = original.resolvePhase
+    copyBuilder.moduleData = original.moduleData
+    copyBuilder.origin = original.origin
+    copyBuilder.attributes = original.attributes.copy()
+    copyBuilder.typeParameters.addAll(original.typeParameters)
+    copyBuilder.status = original.status
+    copyBuilder.returnTypeRef = original.returnTypeRef
+    copyBuilder.deprecationsProvider = original.deprecationsProvider
+    copyBuilder.containerSource = original.containerSource
+    copyBuilder.dispatchReceiverType = original.dispatchReceiverType
+    copyBuilder.contextReceivers.addAll(original.contextReceivers)
+    copyBuilder.name = original.name
+    copyBuilder.initializer = original.initializer
+    copyBuilder.backingField = original.backingField
+    copyBuilder.annotations.addAll(original.annotations)
+    copyBuilder.symbol = original.symbol
+    return copyBuilder.apply(init).build()
+}

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/BuilderConfigurator.kt

@@ -260,6 +260,10 @@ object BuilderConfigurator : AbstractBuilderConfigurator<FirTreeBuilder>(FirTree
             withCopy()
         }
 
+        builder(enumEntry) {
+            withCopy()
+        }
+
         builder(typeOperatorCall) {
             parents += callBuilder
             default("argumentList") {