FIR: add substitution for Java fields

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

@@ -39,7 +39,7 @@ object FirTreeBuilder : AbstractFirTreeBuilder() {
     val variable = element("Variable", Declaration, callableDeclaration, namedDeclaration, statement)
     val valueParameter = element("ValueParameter", Declaration, variable)
     val property = element("Property", Declaration, variable, controlFlowGraphOwner, typeParametersOwner, callableMemberDeclaration)
-    val field = element("Field", Declaration, variable, callableMemberDeclaration) // TODO: add noImpl
+    val field = element("Field", Declaration, variable, callableMemberDeclaration)
     val classLikeDeclaration = element("ClassLikeDeclaration", Declaration, declaration, statement, symbolOwner)
     val klass = element("Class", Declaration, classLikeDeclaration, statement, annotationContainer)
     val regularClass = element("RegularClass", Declaration, memberDeclaration, typeParametersOwner, klass)

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

@@ -49,7 +49,6 @@ object ImplementationConfigurator : AbstractFirTreeImplementationConfigurator()
 
         noImpl(declarationStatus)
         noImpl(resolvedDeclarationStatus)
-        noImpl(field)
 
         val modifiableClass = impl(klass, "FirModifiableClass")
 
@@ -280,6 +279,19 @@ object ImplementationConfigurator : AbstractFirTreeImplementationConfigurator()
             useTypes(backingFieldSymbolType, delegateFieldSymbolType)
         }
 
+        impl(field) {
+            default("isVal") {
+                value = "!isVar"
+                withGetter = true
+            }
+
+            default("resolvePhase") {
+                value = "FirResolvePhase.DECLARATIONS"
+            }
+
+            defaultNull("delegateFieldSymbol", "receiverTypeRef", "initializer", "delegate", "getter", "setter", withGetter = true)
+        }
+
         impl(namedArgumentExpression) {
             default("typeRef") {
                 delegate = "expression"