Livelink/Opentext connector support REST API

Currently, the Livelink connector is based on the Opentext proprietary APIs lapi.jar/lssl.jar

It seems that Opentext/Livelink focuses most of their efforts on the public REST API and lapi.jar becomes deprecated. Hence, a new connector shoule be developed to leverage the REST API.

This task needs to investigate the minimum REST API version needed to provide the Manifold functionality (Repository/Authority connection) similar to the proprietary APIs.

One needs then also to identify the configuration options in the UI, such as

authority connection

• API base Url
• username/password auth (it is not basic auth), NTLM, Kerberos

repository:

• API base url
• API version to use (currently v1 or v2, just in case both version would provide the needed functionality)
• username/password auth (it is not basic auth), NTLM, Kerberos
• path to fetch (e.g. by object id of the folder)
• recursive fetch (yes/no)
• regex pattern for specific filenames
• regex pattern for specific (sub-)folders in case of recursive fetch
• mapping of username to Livelink username
• number of threads for API calls

Then a plan needs to be developed on how to design the functionality. Multi-threading should be used as much as possible, but should be limited to a certain number of threads, e.g. by using a Execution Service,  as the REST API requires many calls to get all information (e.g. to get document categories one needs to "work recursively its way up").

References:

• OpenText REST APIs Content server: https://developer.opentext.com/webaccess/#url=%2Fawd%2Fresources%2Fapis%2Fcs-rest-api-for-cs-16-s&tab=501
• OpenText REST API Directory services (this MIGHT be needed for the Authority plugin, but it MAY also be fine just with the content server APIs): https://developer.opentext.com/webaccess/#url=%2Fawd%2Fresources%2Fapis%2Fotds-16&tab=501
• Executor service fixed thread pool: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Executors.html#newFixedThreadPool(int)