code: public Schema proctime() {
  		if (lastField == null) {
  			throw new ValidationException("No field defined previously. Use field() before.");
  		}
  		tableSchema.get(lastField).put(SCHEMA_PROCTIME, "true");
  		lastField = null;
  		return this;
  	}
docs: Specifies the previously defined field as a processing-time attribute.
  
  <p>E.g. field("proctime", Types.SQL_TIMESTAMP).proctime()