title: Could not read JSON: Cannot construct instance of `java.util.LinkedHashMap`
body: <p>If I got will get an unsure rows JSON data. How should I set of my class?</p>
  
  <p>This is my current class</p>
  
  <pre><code>public class ChatMessage {
  
  private Map&lt;String, String&gt; message = new HashMap&lt;&gt;();
  
  @JsonAnyGetter
  public Map&lt;String, String&gt; any(){
      return this.message;
  }
  
  public Map&lt;String, String&gt; getMessage() {
      return this.message;
  }
  
  @JsonAnySetter
  public void setMessage(String key, String value) {
      message.put(key, value);
  }
  
  @Override
  public String toString() {
      return "Message [message=" + message + "]";
  }
  }
  </code></pre>
  
  <p>this is my json send from js</p>
  
  <pre><code>{"type":"message","user":"james","to":"","message":"Hi every"}
  </code></pre>
  
  <p>I got error now</p>
  
  <pre><code>org.springframework.messaging.converter.MessageConversionException: Could not 
  read JSON: Cannot construct instance of `java.util.LinkedHashMap` (although 
  at least one Creator exists): no String-argument constructor/factory method 
  to deserialize from String value ('Welcome james join the room')
  at [Source: (byte[])" . 
  {"type":"message","user":"james","to":"","message":"Welcome james join the 
  room"}"; line: 1, column: 52] (through reference chain: 
  chat.model.ChatMessage["message"]); nested exception is         
  com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct         
  instance of `java.util.LinkedHashMap` (although at least one Creator exists): 
  no String-argument constructor/factory method to deserialize from String 
  value ('Welcome james join the room')
  at [Source: (byte[])" . 
  {"type":"message","user":"james","to":"","message":"Welcome james join the 
  room"}"; line: 1, column: 52] (through reference chain: 
  chat.model.ChatMessage["message"])
  </code></pre>
  
  <p>because my json would be like </p>
  
  <pre><code>{"type":"message",
   "user":"james",
   "to":"",
   "message":"Welcome james join the room",
   "xxx":"xxxxxxxxxxxxx"}
  </code></pre>
  
  <p>or</p>
  
  <pre><code>{"type":"message",
   "user":"james",
   "to":"",
   "message":"Welcome james join the room",
   "yyy":"xxxxxxxxxxxxx"}
  </code></pre>
  
  <p>how should I set my class?
  Thx</p>