This permission represents "trust" in a signer or codebase.
MBeanTrustPermission contains a target name but no actions list.
A single target name, "register", is defined for this permission.
The target "*" is also allowed, permitting "register" and any future
targets that may be defined.
Only the null value or the empty string are allowed for the action
to allow the policy object to create the permissions specified in
the policy file.
If a signer, or codesource is granted this permission, then it is
considered a trusted source for MBeans. Only MBeans from trusted
sources may be registered in the MBeanServer.