{
  "name": "asignaciones",
  "html": [
      {
          "name": "tarea",
          "caption": "Tarea",
          "type": "select",
          "options" : {
            "t1"    : "tarea1",
            "t2"    : "tarea2",
            "t3"    : "tarea3"
          }
      },
      {
          "name": "ente_asignado",
          "caption": "Asignar a",
          "type": "select",
          "options-load-server" : {
            "method"        : "users.getAll",          
            "field-value"   : "username.value",
            "field-desc"    : "username.value"
          }
      },
      {
          "name": "descripcion",
          "caption": "Descripción tarea",
          "type": "textarea",
          "rows": "5",
          "cols": "70"
      }
  ],
  "actions" : [
      {
          "name": "Create",
          "method":"tasks.create"
      }
  ]
}
{
  "name": "asignaciones",
  "html": [
      {
          "name": "tarea",
          "caption": "Tarea",
          "type": "select",
          "options" : {
            "t1"    : "tarea1",
            "t2"    : "tarea2",
            "t3"    : "tarea3"
          }
      },      
      {
          "name": "ente_asignado",
          "caption": "Asignar a",
          "type": "select",
          "options-load-server" : {
            "method"        : "users.getAll",          
            "field-value"   : "username.value",
            "field-desc"    : "username.value"
          }
      },
      {
          "name": "descripcion",
          "caption": "Descripción tarea",
          "type": "textarea",
          "rows": "5",
          "cols": "70"
      }
  ],
  "actions" : [
      {
          "name": "Create",
          "method":"tasks.create"
      }
  ]
}
Add config in field users to load option from server.
Add config in field users to load option from server.