Java API management library

Not many tags I can apply to this...

I'm developing a Java-based, API-centric web application. By API-centric, I mean it relies on calls to numerous other/external API's to pull-down and enrich data obtained both from those API's as well as other, non-API sources. The external API's are going to be called on a periodic basis and not really based on user-driven events.

Additionally, many of the API's provide both unique as well as overlapping data, making it a bit more complicated to model and process the data with POJO's.

I'm not looking for opinions, but my question is, does anyone knows of any libraries or frameworks that help manage the use of and results from external API's? I don't have an expansive set of requirements in mind, but something along the lines of managing the oauth credentials, the time delays between calls to the API's, potentially merging of results from those API calls, etc.?

Thanks!