code: public String setValue(Field field, String value) {
          return setValue(field.getName(), value);
      }
docs: Sets the value of the given field. Any existing value for that field is
  replaced.
  
  @param field
  The field whose value should be assigned.
  
  @param value
  The value to assign to the given field.
  
  @return
  The previous value of the field, or null if the value of the field
  was not previously defined.