Unlike other subtopics, this is not a configuration page but an explanatory one instead about what Jira content is accessed (and how often) by external tools like IBM Lifecycle Query Engine (LQE) or IBM Link Index Provider (LDX) when fetching data through TRS.
Following is the list of artifacts (and their properties) made accessible to external applications once a functional user is chosen and associated to the LQE/LDX consumer:
Regarding what specific issues from what specific projects will be accessible is a matter of access rights and what projects have been associated with external applications. The first condition for a project to be accessible is to have at least one OSLC association to an external application. This is a configuration done at a project specific level and it determines what Collaboration Links types can be created from Jira. If the Jira project administrator has not configured any association yet, this project will not be accessible from external data sources. The second condition for a project to be accessible is that the functional user must have the "Browse Projects" permission granted on it. This is a configuration done at server level and is a way to prevent some associated projects to be accessible from external data sources. If the Jira server administrator does not grant this permission (or revokes it), external data source(s) will show warning messages about not being able to get/fetch some resources.
Information fetched by external data sources is copied and maintained by them. External data source normally feeds other tools with this data (reports for example) and to prevent performance hits with the information source, it is preferable they have their own copy. Now you may be wondering, if they work with a copy, what happens when the original information changes? For this scenario, external data sources need to constantly check if source information has changed. Default refresh setting on LQE/LDX is one minute. Every minute they ask OSLC Connect for Jira what resources have changed and only that resources are retrieved again to keep their copy updated.
Finally, it is worth saying not all accessible information will be visible to all external data source users (e.g. ELM users). External applications have their own means to grant (or deny) access rights to their users. In the case of LQE, you can check the Configuring LQE Permissions for Jira Projects topic for details.