Allow ConfigParsers to opt-out of the builder generation

Author: knutwalker

annotations/src/main/java/org/neo4j/gds/annotation/Configuration.java

@@ -47,6 +47,8 @@
      */
     String value() default "";
 
+    boolean generateBuilder() default true;
+
     /**
      * By default, a configuration field is resolved in the {@link org.neo4j.gds.core.CypherMapWrapper} parameter with the method name as the expected key.
      * This annotation changes the key to look up to use {@link org.neo4j.gds.annotation.Configuration.Key#value()} instead.

config-generator/src/main/java/org/neo4j/gds/proc/ConfigParser.java

@@ -59,9 +59,12 @@ final class ConfigParser {
         this.typeUtils = typeUtils;
     }
 
-    Spec process(TypeMirror configType) {
+    Spec process(TypeMirror configType, Configuration configAnnotation) {
         TypeElement configElement = asTypeElement(configType);
-        SpecBuilder config = SpecBuilder.builder().root(configElement).rootType(configType);
+        SpecBuilder config = SpecBuilder.builder()
+            .root(configElement)
+            .rootType(configType)
+            .generateBuilder(configAnnotation.generateBuilder());
         process(config, new HashSet<>(), configElement, configElement);
         return config.build();
     }

config-generator/src/main/java/org/neo4j/gds/proc/ConfigurationProcessingStep.java

@@ -83,7 +83,8 @@ private ProcessResult process(Element element) {
             );
             return ProcessResult.INVALID;
         }
-        Spec configSpec = configParser.process(element.asType());
+        var configAnnotation = element.getAnnotation(Configuration.class);
+        Spec configSpec = configParser.process(element.asType(), configAnnotation);
         if (!validClassName(element, configSpec)) {
             messager.printMessage(
                 Diagnostic.Kind.ERROR,

config-generator/src/main/java/org/neo4j/gds/proc/GenerateConfiguration.java

@@ -132,28 +132,33 @@ private TypeSpec process(Spec config, String packageName, String generatedClassN
             builder.addMethod(constructor);
         }
 
-        ClassName builderClassName = ClassName.get(packageName, generatedClassName + ".Builder");
-        TypeSpec configBuilderClass = new GenerateConfigurationBuilder(configParameterName)
-            .defineConfigBuilder(
-                TypeName.get(config.rootType()),
-                implMembers,
-                builderClassName,
-                generatedClassName,
-                constructor.parameters,
-                factory
-            );
+        builder.addMethods(defineMemberMethods(config, fieldDefinitions.names()));
+
+        if (config.generateBuilder()) {
+
+            ClassName builderClassName = ClassName.get(packageName, generatedClassName + ".Builder");
+            TypeSpec configBuilderClass = new GenerateConfigurationBuilder(configParameterName)
+                .defineConfigBuilder(
+                    TypeName.get(config.rootType()),
+                    implMembers,
+                    builderClassName,
+                    generatedClassName,
+                    constructor.parameters,
+                    factory
+                );
 
-        MethodSpec builderFactoryMethod = MethodSpec.methodBuilder("builder")
-            .addModifiers(Modifier.STATIC, Modifier.PUBLIC)
-            .addStatement("return new $T()", builderClassName)
-            .returns(builderClassName)
-            .build();
+            MethodSpec builderFactoryMethod = MethodSpec.methodBuilder("builder")
+                .addModifiers(Modifier.STATIC, Modifier.PUBLIC)
+                .addStatement("return new $T()", builderClassName)
+                .returns(builderClassName)
+                .build();
 
-        return builder
-            .addMethods(defineMemberMethods(config, fieldDefinitions.names()))
-            .addMethod(builderFactoryMethod)
-            .addType(configBuilderClass)
-            .build();
+            builder
+                .addMethod(builderFactoryMethod)
+                .addType(configBuilderClass);
+        }
+
+        return builder.build();
     }
 
     private TypeSpec.Builder classBuilder(Spec config, String packageName, String generatedClassName) {

config-generator/src/main/java/org/neo4j/gds/proc/Spec.java

@@ -44,7 +44,7 @@
 import static com.google.auto.common.MoreElements.isAnnotationPresent;
 
 @GenerateBuilder
-record Spec(TypeElement root, TypeMirror rootType, List<Member> members) {
+record Spec(TypeElement root, TypeMirror rootType, List<Member> members, boolean generateBuilder) {
 
     @GenerateBuilder
     record Member(