Man pages matching name pmdasetendcontextcallback in section 3:

pmdaSetEndContextCallBack.3.en	debian 10 / libpcp-pmda3-dev
pmdaSetEndContextCallBack.3.en	debian 11 / libpcp-pmda3-dev
pmdaSetEndContextCallBack.3.en	debian 12 / libpcp-pmda3-dev