@Override
 public int hashCode() {
   final int prime = 31;
   int result = super.hashCode();
   result = prime * result + ((fieldName == null) ? 0 : fieldName.hashCode());
   result = prime * result + ((function == null) ? 0 : function.hashCode());
   return result;
 }
 @Override
 public boolean equals(Object obj) {
   if (this == obj) return true;
   if (!super.equals(obj)) return false;
   if (getClass() != obj.getClass()) return false;
   PayloadNearQuery other = (PayloadNearQuery) obj;
   if (fieldName == null) {
     if (other.fieldName != null) return false;
   } else if (!fieldName.equals(other.fieldName)) return false;
   if (function == null) {
     if (other.function != null) return false;
   } else if (!function.equals(other.function)) return false;
   return true;
 }