(docs) Add JavaDocs for org.apache.kafka.common.security.oauthbearer.secured (#11811)
(docs) Add JavaDocs for org.apache.kafka.common.security.oauthbearer.secured (#11811)

Reviewers:  Luke Chen <a747209bc9e65a9d7dd7589245c91b7bed721b13@confluent.io>, Jun Rao <junrao@gmail.com>
TiVo/kafka,TiVo/kafka,apache/kafka,lindong28/kafka,apache/kafka,apache/kafka,TiVo/kafka,guozhangwang/kafka,lindong28/kafka,apache/kafka,guozhangwang/kafka,guozhangwang/kafka,lindong28/kafka,lindong28/kafka,TiVo/kafka,guozhangwang/kafka