docs: private ExternalPermissionDefinition toExternalPermissionDefinition(
              String system, String activity) {
          ExternalPermissionDefinition def = ExternalPermissionDefinition.find(system, activity);
          if (def != null) {
              return def;
          }
  
          String delim = "";
          StringBuilder buffer = new StringBuilder();
          for (ExternalPermissionDefinition perm : ExternalPermissionDefinition.values()) {
              buffer.append(delim);
              buffer.append(perm.toString());
              delim = ", ";
          }
  
          throw new IllegalArgumentException(
                  "Permission type "
                          + system
                          + "."
                          + activity
                          + " is not supported.  "
                          + "The only supported permissions at this time are: "
                          + buffer.toString());
      }