Setting isolation-level through rdf4j 3.7.4 client side is not compatible with server side from another version

[DenitsaStoianova]

Current Behavior

Trying to set isolation-level through rdf4j 3.7.4 client side leads to java.lang.IllegalArgumentException: Unknown isolation-level setting http://www.openrdf.org/schema/sesame#READ_COMMITTED when server side version is >= 4.1.3

Expected Behavior

Isolation-level must be successfully set regardless of client or server side versions.

Steps To Reproduce

1. Connect to remote repository and begin a new transaction with READ_COMMITTED isolation-level.
   Notes: client side rdf4j version is 3.7.4 while server side is >= 4.1.3

HTTPRepository repository = new HTTPRepository("remote_repository_url");

try (RepositoryConnection conn = repository.getConnection()) {
    conn.begin(IsolationLevels.READ_COMMITTED);
} 

2. IllegalArgumentException is thrown:

java.lang.IllegalArgumentException: Unknown isolation-level setting http://www.openrdf.org/schema/sesame#READ_COMMITTED
	at org.eclipse.rdf4j.http.server.repository.transaction.TransactionStartController.getIsolationLevel(TransactionStartController.java:92)
	at org.eclipse.rdf4j.http.server.repository.transaction.TransactionStartController.startTransaction(TransactionStartController.java:129)
	at org.eclipse.rdf4j.http.server.repository.transaction.TransactionStartController.handleRequestInternal(TransactionStartController.java:68)
	at org.springframework.web.servlet.mvc.AbstractController.handleRequest(AbstractController.java:177)

Version

4.2.0

Are you interested in contributing a solution yourself?

Yes

Anything else?

No response

[hmottestad]

Maybe this is caused by #4185 ?

It is also possible that this didn't work correctly before 4.1.3, but that there was no error message which made the bug go unnoticed.

[DenitsaStoianova]

Yes, the problem comes from fixes for REST Isolation-level settings in #4185 where IllegalArgumentException for Unknown isolation-level setting is introduced.

Also, there are another problems with isolation-level settings in versions before 4.1.3:

rdf4j client 3.7.4 adds the following properties to the request:

isolation-level=http://www.openrdf.org/schema/sesame#READ_COMMITTED
transaction-setting__org.eclipse.rdf4j.IsolationLevel=READ_COMMITTED

When the request is processed in TransactionStartController none of the isolation-level parameters are set to the transaction because it cannot find the appropriate matches due to the following problems:

1. The first parameter isolation-level=http://www.openrdf.org/schema/sesame#READ_COMMITTED is not used in the correct way because it try to compare the value http://www.openrdf.org/schema/sesame#READ_COMMITTED with READ_COMMITTED.

2. In rdf4j 4.0.0 IsolationLevel interface is moved in another package which changes the second request parameter to the following one: transaction-setting__org.eclipse.rdf4j.common.transaction.IsolationLevel=READ_COMMITTED which is not the same as the expected one.

As a result, setting the isolation-level through client side versions < 4.0.0 is not compatible with server side versions >= 4.0.0