How to use the @graphql-codegen/java-common.JavaDeclarationBlock function in @graphql-codegen/java-common

const fieldName = this.getFieldName(field);
      const isLastField = nonIdFields.length - 1 === idx ? true : false;
      const returnType = isLastField ? 'Build' : nonIdFields[idx + 1].name;
      const interfaceName = this.getStepInterfaceName(field.name);
      const interfaceDeclaration = new JavaDeclarationBlock()
        .asKind('interface')
        .withName(interfaceName)
        .access('public');
      interfaceDeclaration.withBlock(
        indent(`${this.getStepInterfaceName(returnType)} ${fieldName}(${this.getNativeType(field)} ${fieldName});`)
      );
      return interfaceDeclaration;
    });

    // Builder
    const builder = new JavaDeclarationBlock()
      .asKind('interface')
      .withName(this.getStepInterfaceName('Build'))
      .access('public');
    const builderBody = [];
    builderBody.push(`${this.getModelName(model)} build();`);
    nullableFields.forEach((field, idx) => {
      const fieldName = this.getFieldName(field);
      builderBody.push(`${this.getStepInterfaceName('Build')} ${fieldName}(${this.getNativeType(field)} ${fieldName});`);
    });

    builder.withBlock(indentMultiline(builderBody.join('\n')));
    return [...interfaces, builder];
  }

protected generateBuilderClass(model: CodeGenModel, classDeclaration: JavaDeclarationBlock): void {
    const nonNullableFields = model.fields.filter(field => !field.isNullable);
    const nullableFields = model.fields.filter(field => field.isNullable);
    const writeableFields = nullableFields.filter((field: CodeGenField) => !this.READ_ONLY_FIELDS.includes(field.name));
    const stepInterfaces = writeableFields.map((field: CodeGenField) => {
      return this.getStepInterfaceName(field.name);
    });

    const builderClassDeclaration = new JavaDeclarationBlock()
      .access('public')
      .static()
      .asKind('class')
      .withName('Builder')
      .implements([...stepInterfaces, this.getStepInterfaceName('Build')]);

    // Add private instance fields
    [...nonNullableFields, ...nullableFields].forEach((field: CodeGenField) => {
      const fieldName = this.getFieldName(field);
      builderClassDeclaration.addClassMember(fieldName, this.getNativeType(field), '', undefined, 'private');
    });

    // methods
    // build();
    builderClassDeclaration.addClassMethod(
      'build',

ObjectTypeDefinition(node: ObjectTypeDefinitionNode): string {
    return new JavaDeclarationBlock()
      .access('public')
      .asKind('interface')
      .withName(this.convertName(node.name))
      .withComment(node.description)
      .withBlock(node.fields.map(f => indent((f as any)(false))).join('\n')).string;
  }

public wrapWithClass(content: string): string {
    return new JavaDeclarationBlock()
      .access('public')
      .asKind('class')
      .withName(this.config.className)
      .withBlock(indentMultiline(content)).string;
  }

const fragmentsClassName = 'Fragments';

      childFields.push({
        isObject: true,
        isList: false,
        isFragment: true,
        rawType: options.schemaType,
        type: options.schemaType,
        isNonNull: true,
        annotation: 'Nonnull',
        className: fragmentsClassName,
        fieldName: 'fragments',
      });

      const fragmentsClass = new JavaDeclarationBlock()
        .withName(fragmentsClassName)
        .access('public')
        .static()
        .final()
        .asKind('class');

      const fragmentMapperClass = new JavaDeclarationBlock()
        .withName('Mapper')
        .access('public')
        .static()
        .final()
        .implements([`FragmentResponseFieldMapper<${fragmentsClassName}>`])
        .asKind('class');

      fragmentsClass.addClassMethod(
        fragmentsClassName,

private createBuilderClass(parentClassName: string, variables: ReadonlyArray): JavaDeclarationBlock {
    const builderClassName = 'Builder';
    const cls = new JavaDeclarationBlock()
      .static()
      .final()
      .access('public')
      .asKind('class')
      .withName(builderClassName)
      .addClassMethod(builderClassName, null, '');

    variables.forEach(variable => {
      const baseTypeNode = getBaseTypeNode(variable.type);
      const schemaType = this._schema.getType(baseTypeNode.name.value);
      const javaClass = this.getJavaClass(schemaType);
      const annotation = isNonNullType(variable.type) ? 'Nonnull' : 'Nullable';
      this._imports.add(Imports[annotation]);
      cls.addClassMember(variable.variable.name.value, javaClass, null, [annotation], 'private');
      cls.addClassMethod(
        variable.variable.name.value,

OperationDefinition(node: OperationDefinitionNode): string {
    this.visitingFragment = false;
    const operationType = toPascalCase(node.operation);
    const operationSchemaType = this.getRootType(node.operation);
    const className = node.name.value.endsWith(operationType) ? operationType : `${node.name.value}${operationType}`;
    this._imports.add(Imports[operationType]);
    this._imports.add(Imports.String);
    this._imports.add(Imports.Override);
    this._imports.add(Imports.Generated);
    this._imports.add(Imports.OperationName);
    this._imports.add(Imports.Operation);
    this._imports.add(Imports.ResponseFieldMapper);

    const cls = new JavaDeclarationBlock()
      .annotate([`Generated("Apollo GraphQL")`])
      .access('public')
      .final()
      .asKind('class')
      .withName(className);

    const printed = this.printDocument(node);

    cls.implements([`${operationType}<${className}.Data, ${className}.Data, ${node.variableDefinitions.length === 0 ? 'Operation' : className}.Variables>`]);

    cls.addClassMember('OPERATION_DEFINITION', 'String', `"${printed}"`, [], 'public', { static: true, final: true });
    cls.addClassMember('QUERY_DOCUMENT', 'String', 'OPERATION_DEFINITION', [], 'public', { static: true, final: true });
    cls.addClassMember(
      'OPERATION_NAME',
      'OperationName',
      `new OperationName() {

private transformSelectionSet(options: TransformSelectionSetOptions, isRoot = true) {
    if (!options.result) {
      options.result = {};
    }

    if (!isObjectType(options.schemaType) && !isInterfaceType(options.schemaType)) {
      return options.result;
    }

    const className = this.createUniqueClassName(Object.keys(options.result), options.className);
    const cls = new JavaDeclarationBlock()
      .access('public')
      .asKind('class')
      .withName(className)
      .implements(options.implements || []);

    if (!options.nonStaticClass) {
      cls.static();
    }

    options.result[className] = cls;

    const fields = options.schemaType.getFields();
    const childFields: ChildField[] = [...(options.additionalFields || [])];
    const childInlineFragments: { onType: string; node: InlineFragmentNode }[] = [];
    const childFragmentSpread: LoadedFragment[] = [...(options.additionalFragments || [])];