final Java fields should not be mutable.

compiler-plugin/src/main/kotlin/com/google/devtools/ksp/symbol/impl/java/KSPropertyDeclarationJavaImpl.kt

@@ -42,7 +42,8 @@ class KSPropertyDeclarationJavaImpl private constructor(val psi: PsiField) :
         psi.toLocation()
     }
 
-    override val isMutable: Boolean = true
+    override val isMutable: Boolean
+        get() = !modifiers.contains(Modifier.FINAL)
 
     override val hasBackingField: Boolean
         get() = true

kotlin-analysis-api/src/main/kotlin/com/google/devtools/ksp/impl/symbol/kotlin/AbstractKSDeclarationImpl.kt

@@ -26,6 +26,7 @@ import com.google.devtools.ksp.symbol.Location
 import com.google.devtools.ksp.symbol.Modifier
 import com.google.devtools.ksp.symbol.Origin
 import com.google.devtools.ksp.toKSModifiers
+import com.intellij.psi.PsiModifierListOwner
 import org.jetbrains.kotlin.analysis.api.symbols.KtDeclarationSymbol
 import org.jetbrains.kotlin.analysis.api.symbols.KtNamedClassOrObjectSymbol
 import org.jetbrains.kotlin.analysis.api.symbols.markers.KtNamedSymbol
@@ -47,7 +48,11 @@ abstract class AbstractKSDeclarationImpl(val ktDeclarationSymbol: KtDeclarationS
     }
 
     override val modifiers: Set<Modifier> by lazy {
-        (ktDeclarationSymbol.psi as? KtModifierListOwner)?.toKSModifiers() ?: emptySet()
+        when (val psi = ktDeclarationSymbol.psi) {
+            is KtModifierListOwner -> psi.toKSModifiers()
+            is PsiModifierListOwner -> psi.toKSModifiers()
+            else -> emptySet()
+        }
     }
 
     override val containingFile: KSFile? by lazy {

kotlin-analysis-api/src/main/kotlin/com/google/devtools/ksp/impl/symbol/kotlin/KSPropertyDeclarationJavaImpl.kt

@@ -1,16 +1,7 @@
 package com.google.devtools.ksp.impl.symbol.kotlin
 
 import com.google.devtools.ksp.KSObjectCache
-import com.google.devtools.ksp.symbol.KSExpectActual
-import com.google.devtools.ksp.symbol.KSName
-import com.google.devtools.ksp.symbol.KSPropertyDeclaration
-import com.google.devtools.ksp.symbol.KSPropertyGetter
-import com.google.devtools.ksp.symbol.KSPropertySetter
-import com.google.devtools.ksp.symbol.KSType
-import com.google.devtools.ksp.symbol.KSTypeParameter
-import com.google.devtools.ksp.symbol.KSTypeReference
-import com.google.devtools.ksp.symbol.KSVisitor
-import com.google.devtools.ksp.symbol.Origin
+import com.google.devtools.ksp.symbol.*
 import org.jetbrains.kotlin.analysis.api.symbols.KtJavaFieldSymbol
 
 class KSPropertyDeclarationJavaImpl private constructor(private val ktJavaFieldSymbol: KtJavaFieldSymbol) :
@@ -35,7 +26,7 @@ class KSPropertyDeclarationJavaImpl private constructor(private val ktJavaFieldS
     }
 
     override val isMutable: Boolean
-        get() = true
+        get() = !modifiers.contains(Modifier.FINAL)
 
     override val hasBackingField: Boolean
         get() = true

test-utils/src/main/kotlin/com/google/devtools/ksp/processor/DefaultFunctionProcessor.kt

@@ -17,6 +17,7 @@
 
 package com.google.devtools.ksp.processor
 
+import com.google.devtools.ksp.getClassDeclarationByName
 import com.google.devtools.ksp.getDeclaredFunctions
 import com.google.devtools.ksp.isAbstract
 import com.google.devtools.ksp.processing.Resolver
@@ -97,6 +98,8 @@ class DefaultFunctionProcessor : AbstractTestProcessor() {
         )
         val aProperty = abstractClass.declarations.single { it.simpleName.asString() == "a" } as KSPropertyDeclaration
         result.add("${aProperty.simpleName.asString()}: ${aProperty.isAbstract()}")
+        val D = resolver.getClassDeclarationByName("D")!!
+        D.getAllProperties().forEach { result.add("${it.simpleName.asString()}: isMutable: ${it.isMutable}") }
         return emptyList()
     }
 

test-utils/testData/api/interfaceWithDefault.kt

@@ -33,6 +33,8 @@
 // abstractVar: isAbstract: true: isMutable: true
 // abstractProperty: isAbstract: true: isMutable: false
 // a: false
+// normalField: isMutable: true
+// finalField: isMutable: false
 // END
 // FILE: a.kt
 interface KTInterface: Sequence<String> {
@@ -66,3 +68,11 @@ interface C {
 
     int bar()
 }
+
+// FILE: D.java
+
+class D {
+    int normalField;
+
+    final int finalField;
+}