code: public AttributeValue withM(java.util.Map<String, AttributeValue> m) {
          setM(m);
          return this;
      }
docs: <p>
  An attribute of type Map. For example:
  </p>
  <p>
  <code>"M": {"Name": {"S": "Joe"}, "Age": {"N": "35"}}</code>
  </p>
  
  @param m
  An attribute of type Map. For example:</p>
  <p>
  <code>"M": {"Name": {"S": "Joe"}, "Age": {"N": "35"}}</code>
  @return Returns a reference to this object so that method calls can be chained together.