来自gson-2.8.6.jar

package com.google.gson.reflect;
...
public class TypeToken<T> {
  final Class<? super T> rawType;
  final Type type;
  final int hashCode;

  /**
   * Constructs a new type literal. Derives represented class from type
   * parameter.
   *
   * <p>Clients create an empty anonymous subclass. Doing so embeds the type
   * parameter in the anonymous class's type hierarchy so we can reconstitute it
   * at runtime despite erasure.
   */
  @SuppressWarnings("unchecked")
  protected TypeToken() {
    this.type = getSuperclassTypeParameter(getClass());
    this.rawType = (Class<? super T>) $Gson$Types.getRawType(type);
    this.hashCode = type.hashCode();
  }

  /**
   * Unsafe. Constructs a type literal manually.
   */
  @SuppressWarnings("unchecked")
  TypeToken(Type type) {
    this.type = $Gson$Types.canonicalize($Gson$Preconditions.checkNotNull(type));
    this.rawType = (Class<? super T>) $Gson$Types.getRawType(this.type);
    this.hashCode = this.type.hashCode();
  }
...
}

在包com.google.gson.reflect之外，为什么protected TypeToken()构造函数可以用来新建一个示例？
{}出现在new TypeToken<String>()之后的语法是什么？

package com.dataservice.controller;

...
Type localVarReturnType = (new TypeToken<String>() {}).getType();
...