code: public SendUsersMessageRequest withUsers(java.util.Map<String, EndpointSendConfiguration> users) {
          setUsers(users);
          return this;
      }
docs: A map that associates user IDs with EndpointSendConfiguration objects. Within an EndpointSendConfiguration
  object, you can tailor the message for a user by specifying message overrides or substitutions.
  
  @param users
  A map that associates user IDs with EndpointSendConfiguration objects. Within an EndpointSendConfiguration
  object, you can tailor the message for a user by specifying message overrides or substitutions.
  @return Returns a reference to this object so that method calls can be chained together.