src/main/java/com/conveyal/gtfs/loader/ColorField.java
public ValidateFieldResult<String> validateAndConvert (String string) {
        ValidateFieldResult<String> result = new ValidateFieldResult<>(string);
        try {
            if (string.length() != 6) {
                result.errors.add(NewGTFSError.forFeed(NewGTFSErrorType.COLOR_FORMAT, string));
            }
            int integer = Integer.parseInt(string, 16);
            return result; // Could also store the integer.
        } catch (Exception ex) {
            throw new StorageException(NewGTFSErrorType.COLOR_FORMAT, string);
        }
    }
public ValidateFieldResult<String> validateAndConvert (String string) {
        ValidateFieldResult<String> result = new ValidateFieldResult<>(string);
        try {
            if (string.length() != 6) {
                result.errors.add(NewGTFSError.forFeed(NewGTFSErrorType.COLOR_FORMAT, string));
            }
            int integer = Integer.parseInt(string, 16);
            return result; // Could also store the integer.
        } catch (Exception ex) {
            throw new StorageException(NewGTFSErrorType.COLOR_FORMAT, string);
        }
    }
Check that a string can be properly parsed and is in range.