<Environment name="foo/principalName" 
  type="java.lang.String" 
  override="false"
  value="foo" />
<Environment name="foo/allowedFrom" 
  type="java.lang.String" 
  override="false"
  value="localhost,${T{trusted.hostname}}${T_perl{$internal = property('trusted.internal_hostname');$internal?",$internal":''}}" />