【GsonBuilder】The method's class,

环境背景
IDEA，创建一个Springboot2 MAVEN工程，POM文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>lcn-parent</artifactId>
        <groupId>com.springcloud</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>basics</artifactId>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR3</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.1</version>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

抛出如下异常

***************************
APPLICATION FAILED TO START
***************************

Description:

An attempt was made to call a method that does not exist. The attempt was made from the following location:

    java.lang.invoke.MethodHandleNatives.resolve(Native Method)

The following method did not exist:

    com.google.gson.GsonBuilder.setLenient()Lcom/google/gson/GsonBuilder;

The method's class, com.google.gson.GsonBuilder, is available from the following locations:

    jar:file:/Users/apple/.m2/repository/com/google/code/gson/gson/2.1/gson-2.1.jar!/com/google/gson/GsonBuilder.class

It was loaded from the following location:

    file:/Users/apple/.m2/repository/com/google/code/gson/gson/2.1/gson-2.1.jar


Action:

Correct the classpath of your application so that it contains a single, compatible version of com.google.gson.GsonBuilder


Process finished with exit code 1

解决方法：
在父工程pom文件中添加