public JCNewClass build() {
    // Generate a subclass of Callable
    ListBuffer<JCTree> classBody = new ListBuffer<JCTree>();
    int numParams = paramLists.getParameters().size();
    int minimumParams = 0;
    for (Parameter p : paramLists.getParameters()) {
      if (p.isDefaulted() || p.isSequenced()) break;
      minimumParams++;
    }
    boolean isVariadic = minimumParams != numParams;
    if (parameterListTree != null) {
      // generate a method for each defaulted param
      for (Tree.Parameter p : parameterListTree.getParameters()) {
        if (p.getDefaultArgument() != null || p.getDeclarationModel().isSequenced()) {
          MethodDefinitionBuilder methodBuilder =
              gen.classGen().makeParamDefaultValueMethod(false, null, parameterListTree, p);
          classBody.append(methodBuilder.build());
        }
      }
    }

    // collect each parameter type from the callable type model rather than the declarations to get
    // them all bound
    java.util.List<ProducedType> parameterTypes = new ArrayList<ProducedType>(numParams);
    if (forwardCallTo != null) {
      for (int i = 0; i < numParams; i++)
        parameterTypes.add(gen.getParameterTypeOfCallable(typeModel, i));
    } else {
      // get them from our declaration
      for (Parameter p : paramLists.getParameters()) parameterTypes.add(p.getType());
    }

    // now generate a method for each supported minimum number of parameters below 4
    // which delegates to the $call$typed method if required
    for (int i = minimumParams, max = Math.min(numParams, 4); i < max; i++) {
      classBody.append(makeDefaultedCall(i, isVariadic, parameterTypes));
    }
    // generate the $call method for the max number of parameters,
    // which delegates to the $call$typed method if required
    classBody.append(makeDefaultedCall(numParams, isVariadic, parameterTypes));
    // generate the $call$typed method if required
    if (isVariadic && forwardCallTo == null)
      classBody.append(makeCallTypedMethod(body, parameterTypes));

    JCClassDecl classDef =
        gen.make().AnonymousClassDef(gen.make().Modifiers(0), classBody.toList());

    JCNewClass instance =
        gen.make()
            .NewClass(
                null,
                null,
                gen.makeJavaType(typeModel, JT_EXTENDS | JT_CLASS_NEW),
                List.<JCExpression>of(gen.make().Literal(typeModel.getProducedTypeName(true))),
                classDef);
    return instance;
  }
 private JCTree makeDefaultedCall(
     int i, boolean isVariadic, java.util.List<ProducedType> parameterTypes) {
   // collect every parameter
   int a = 0;
   ListBuffer<JCStatement> stmts = new ListBuffer<JCStatement>();
   for (Parameter param : paramLists.getParameters()) {
     // don't read default parameter values for forwarded calls
     if (forwardCallTo != null && i == a) break;
     // read the value
     JCExpression paramExpression = getTypedParameter(param, a, i > 3, parameterTypes);
     JCExpression varInitialExpression;
     if (param.isDefaulted() || param.isSequenced()) {
       if (i > 3) {
         // must check if it's defined
         JCExpression test =
             gen.make()
                 .Binary(JCTree.GT, gen.makeSelect(getParamName(0), "length"), gen.makeInteger(a));
         JCExpression elseBranch = makeDefaultValueCall(param, a);
         varInitialExpression = gen.make().Conditional(test, paramExpression, elseBranch);
       } else if (a >= i) {
         // get its default value because we don't have it
         varInitialExpression = makeDefaultValueCall(param, a);
       } else {
         // we must have it
         varInitialExpression = paramExpression;
       }
     } else {
       varInitialExpression = paramExpression;
     }
     // store it in a local var
     JCStatement var =
         gen.make()
             .VarDef(
                 gen.make().Modifiers(Flags.FINAL),
                 gen.naming.makeUnquotedName(getCallableTempVarName(param)),
                 gen.makeJavaType(
                     parameterTypes.get(a),
                     CodegenUtil.isUnBoxed(param) ? 0 : gen.JT_NO_PRIMITIVES),
                 varInitialExpression);
     stmts.append(var);
     a++;
   }
   if (forwardCallTo != null) {
     InvocationBuilder invocationBuilder =
         InvocationBuilder.forCallableInvocation(gen, forwardCallTo, paramLists, i);
     boolean prevCallableInv = gen.expressionGen().withinCallableInvocation(true);
     try {
       stmts.append(gen.make().Return(invocationBuilder.build()));
     } finally {
       gen.expressionGen().withinCallableInvocation(prevCallableInv);
     }
   } else if (isVariadic) {
     // chain to n param typed method
     List<JCExpression> args = List.nil();
     // pass along the parameters
     for (a = paramLists.getParameters().size() - 1; a >= 0; a--) {
       Parameter param = paramLists.getParameters().get(a);
       args = args.prepend(gen.makeUnquotedIdent(getCallableTempVarName(param)));
     }
     JCMethodInvocation chain =
         gen.make().Apply(null, gen.makeUnquotedIdent(Naming.getCallableTypedMethodName()), args);
     stmts.append(gen.make().Return(chain));
   } else {
     // insert the method body directly
     stmts.appendList(this.body);
   }
   List<JCStatement> body = stmts.toList();
   return makeCallMethod(body, i);
 }