private Optional<String> validateProctimeAttribute(Optional<String> proctimeAttribute) {
		return proctimeAttribute.map((attribute) -> {
			// validate that field exists and is of correct type
			Optional<TypeInformation<?>> tpe = schema.getFieldType(attribute);
			if (!tpe.isPresent()) {
				throw new ValidationException("Processing time attribute '" + attribute + "' is not present in TableSchema.");
			} else if (tpe.get() != Types.SQL_TIMESTAMP()) {
				throw new ValidationException("Processing time attribute '" + attribute + "' is not of type SQL_TIMESTAMP.");
			}
			return attribute;
		}
private Optional < String > validateProctimeAttribute ( Optional < String > proctimeAttribute ) { return proctimeAttribute . map ( ( attribute ) -> { Optional < TypeInformation < ? > > tpe = schema . getFieldType ( attribute ) ; if ( ! tpe . isPresent ( ) ) { throw new ValidationException ( "Processing time attribute '" + attribute + "' is not present in TableSchema." ) ; } else if ( tpe . get ( ) != Types . SQL_TIMESTAMP ( ) ) { throw new ValidationException ( "Processing time attribute '" + attribute + "' is not of type SQL_TIMESTAMP." ) ; } return attribute ; }
Validates a field of the schema to be the processing time attribute.

@param proctimeAttribute The name of the field that becomes the processing time field.