Unable to perform KV Operations by external LDAP users using PLAIN auth mechanism

The code uses external user (LDAP user) to authenticate to CB server using PLAIN auth.

On 6.6.0 - 7813 CB Server - The code connects to the cluster and performs KV operations. On trying to do KV operations - upsert/get , the code fails with - "Authentication failed. This could be due to invalid credentials or if the user is an external user the external authentication service may not support the selected authentication mechanism." 

But the same code passes for 6.5.0 - 4960 CB Server successfully with KV Operations.

external-auth.java

6.6log.txt