I am working on CDH 5.16 by reading TLS configuration documents.
This document asks you to use the Oracle JDK path as JAVA_HOME.
But, this document states that OpenJDK is supported in CDH 5.16.
Is it possible to use OpenJDK when setting up Cloudera Manager TLS in CDH 5.16?
Yes of course you can use OpenJDK for TLS encryption. The use of "Oracle JDK" on this page is historical and does not indicate a restriction, think of it as "Oracle JDK or OpenJDK"
Please review the JDK requirements, JDK 7 and JDK 8 versions are certified for CM / CDH 5.x series.