Claims Request Body is not readable

We do use the Policy Enforcer and want to forward parameters to a CIP via the 'parameters' feature. The initial paramaters are received as as JSON in the request body:

"policy-enforcer": {
   .....
  "parameters": {
     "AAA": "{request.body['/aaa']}",
    "BBB": "{request.body['/bbb']}",
    "CCC": "{request.body['/bbb']}"
  }
}

AAA BBB and CCC are alwas empty despite a correct request. This is due to
the org.keycloak.adapters.authorization.util.RequestPlaceHolderResolver which tries to see if there is anything to read in line 110:

   if (body == null || body.available() == 0) {
      return Collections.emptyList();
    }

Due to coyote/catalina InputBuffer which always returns 0 despite being readable it will always return the empty collection. If hooked with a debugger and returning something else than 0 everything works as expected.

We do use JBoss EAP 6.4 and apache-tomcat-7.0.32 both do use catalina and thus are affected by this issue.

A workaround could be just reading one byte:

  if (body == null || (body.markSupported()) ? body.read() < 0 : body.available() == 0) {
      return Collections.emptyList();
    }

a few lines later the stream gets reseted anyways:

      if (body.markSupported()) {
                body.mark(0);
            }

Anyways wouldn't it be more straight forward to read the stream completly at the beginning and skip these validation steps at all?