/**
* Attempts to parse the version header and return a corresponding {@link AcceptAPIVersion}
* representation. Further validates that the specified versions are valid. That being not in the
* future and no earlier that the current major version.
*
* @param req The HTTP servlet request
* @return A non-null {@link AcceptAPIVersion} instance
* @throws BadRequestException If an invalid version is requested
*/
private AcceptAPIVersion parseAcceptAPIVersion(final HttpServletRequest req)
throws BadRequestException {
// Extract out the protocol and resource versions.
final String versionString = req.getHeader(ACCEPT_API_VERSION);
final AcceptAPIVersion acceptAPIVersion =
AcceptAPIVersion.newBuilder(versionString)
.withDefaultProtocolVersion(PROTOCOL_VERSION)
.expectsProtocolVersion()
.build();
final Version protocolVersion = acceptAPIVersion.getProtocolVersion();
if (protocolVersion.getMajor() != PROTOCOL_VERSION.getMajor()) {
throw new BadRequestException("Unsupported major version: " + protocolVersion);
}
if (protocolVersion.getMinor() > PROTOCOL_VERSION.getMinor()) {
throw new BadRequestException("Unsupported minor version: " + protocolVersion);
}
return acceptAPIVersion;
}