A few properties are not documented.
This property is used as an alias to get password from credential providers, or, fall back to using the value as password in clear text. There is also a caveat that credential providers can not be a HDFS-based file system, as mentioned in
HADOOP-11934, to prevent cyclic dependency issue.
This should be documented in core-default.xml and GroupsMapping.md
This property controls whether or not to fall back to storing credential password as cleartext.
This should be documented in core-default.xml.
This is mentioned in CredentialProvider API Guide, but not in core-default.xml
The "Supported Features" in CredentialProvider API Guide should link back to GroupsMapping.md#LDAP Groups Mapping
This is the password file to protect credential files.