The adapters provide components that either:
open-connectors are connectors that support the Open Connector Framework (OCF) - see the open-connector-framework module. This is the principle (preferred) mechanism for supporting pluggable components in the open metadata implementation. The OCF has additional uses in providing reusable/pluggable components for external technology - particularly related to data access.
authentication-plugins support extensions to technology such as LDAP that are used to verify the identity of an individual or service requesting access to data/metadata.
governance-engines-plugins support plugins to governance engines to enable them to use open metadata settings in their validation and enforcement decisions and the resulting actions they take.