Jira-rest-java-client-core backwards compatibility

Hi people,

Support have asked me to post here as jira-rest-java-client-core is no longer supported by Atlassian.

I’m supporting a client that is currently using jira-rest-java-client-core-5.1.0 to support Jira integrations for x6 customers that were all using Jira Server.

One has moved to cloud and can no longer use this package because the name is no longer returned and they get the error:
Caused by: org.codehaus.jettison.json.JSONException: JSONObject[“name”] not found.

I know the fix is to update to a later package but the other x5 customers are sharing the use of the same package to connect to Jira Server and they all utilize the 5.1.0 package.

If I upgrade the package will this break functionality for the integrations that are still connecting to Jira Server instances?

Thanks in advance!