code: public void setValue(String fieldRefName, boolean returnedByProcedure)
      {
          this.fieldSource = SOURCE_FIELD;
          this.fieldRefName = fieldRefName;
          this.returnedByProcedure = returnedByProcedure;
          this.constantValue = null;
  
          // If the field reference is not valid, then disregard the value
          // of the returnedByProcedure argument.
          if (this.getFieldRef() == null)
          {
              this.returnedByProcedure = false;
          }
  
          // If the field reference is not valid, then disregard the value
          // of the returnedByProcedure argument.
          if (this.getFieldRef() == null)
          {
              this.returnedByProcedure = false;
          }
      }
docs: Sets up this object to represent a value that is derived from a field
  in the corresponding class-descriptor.
  <p>
  If the value of <code>fieldRefName</code> is blank or refers to an
  invalid field reference, then the value of the corresponding argument
  will be set to null. In this case, {@link #getIsReturnedByProcedure}
  will be set to <code>false</code>, regardless of the value of the
  <code>returnedByProcedure</code> argument.
  
  @param fieldRefName the name of the field reference that provides the
  value of this argument.
  @param returnedByProcedure indicates that the value of the argument
  is returned by the procedure that is invoked.