如何在请求正文中添加我的内容？Groovy

@Grab('org.apache.httpcomponents:httpclient:4.5.13')
import org.apache.http.client.methods.HttpPost
import org.apache.http.entity.StringEntity
import org.apache.http.impl.client.CloseableHttpClient
import org.apache.http.impl.client.HttpClients

// 创建HTTP客户端
CloseableHttpClient httpClient = HttpClients.createDefault()

// 创建HTTP POST请求对象
HttpPost httpPost = new HttpPost("https://example.com/api/endpoint")
httpPost.addHeader("Content-Type", "application/json")

// 创建要添加的内容
def myContent = "Hello, World!"

// 将内容插入到请求正文中
def requestBody = """
{
  "message": "${myContent}"
}
"""

// 设置请求正文
httpPost.setEntity(new StringEntity(requestBody, "UTF-8"))

// 发送HTTP请求并获取响应
def response = httpClient.execute(httpPost)

// 处理响应结果
def responseBody = EntityUtils.toString(response.getEntity())
println("Response Body: ${responseBody}")

// 关闭HTTP客户端
httpClient.close()