code: public boolean isFieldChain() {
  		if (operationsChain == null) {
  			return true;
  		}
  
  		for (OPair<Integer, List<String>> pair : operationsChain) {
  			if (!pair.getKey().equals(OSQLFilterFieldOperator.FIELD.id)) {
  				return false;
  			}
  		}
  
  		return true;
  	}
docs: Check whether or not this filter item is chain of fields (e.g. "field1.field2.field3"). Return true if filter item contains
  only field projections operators, if field item contains any other projection operator the method returns false. When filter
  item does not contains any chain operator, it is also field chain consist of one field.
  
  @return whether or not this filter item can be represented as chain of fields.