JavaField macro: within a class, don't generate "nonmutating" modifier

Author: DougGregor

Sources/JavaKitMacros/JavaFieldMacro.swift

@@ -64,9 +64,14 @@ extension JavaFieldMacro: AccessorMacro {
       getter
     ]
 
+    let nonmutatingModifier =
+      (context.lexicalContext.first?.is(ClassDeclSyntax.self) ?? false)
+        ? ""
+        : "nonmutating "
+
     if createSetter {
       let setter: AccessorDeclSyntax = """
-        nonmutating set { self[javaFieldName: \(literal: fieldName), fieldType: \(fieldType).self] = newValue }
+        \(raw: nonmutatingModifier)set { self[javaFieldName: \(literal: fieldName), fieldType: \(fieldType).self] = newValue }
         """
       accessors.append(setter)
     }

Tests/JavaKitMacroTests/JavaClassMacroTests.swift

@@ -167,15 +167,15 @@ class JavaKitMacroTests: XCTestCase {
               get {
                   self[javaFieldName: "myField", fieldType: Int64.self]
               }
-              nonmutating set {
+              set {
                   self[javaFieldName: "myField", fieldType: Int64.self] = newValue
               }
           }
           public var objectField: JavaObject! {
               get {
                   self[javaFieldName: "objectField", fieldType: JavaObject?.self]
               }
-              nonmutating set {
+              set {
                   self[javaFieldName: "objectField", fieldType: JavaObject?.self] = newValue
               }
           }