An uncaught runtime error occured. custom structuring

[kent-sil]

running the oscal-cli profile resolve command on a validated profile, responds with the error: "An uncaught runtime error occured. custom structuring". I am using the Merge -- Custom directive.

code snippet:

  <imports>
    <href>control-catalog-link</href>
    <include-controls>
      <with-ids>ctl_1.1</with-ids>
      <with-ids>ctl_1.2</with-ids>
      <with-ids>ctl_1.3</with-ids>
      <with-ids>ctl_1.4</with-ids>
    </include-controls>
  </imports>
  <merge>
    <custom>
      <groups>
        <id>grp_1</id>
        <class>control-group</class>
        <title>Reporting Controls</title>
        <groups>
          <id>ctl_1.1</id>
          <title>Reports</title>
          <class>control</class>
          <insert-controls>
            <include-controls>
              <with-ids>ctl_1.1</with-ids>
              <with-ids>ctl_1.2</with-ids>
            </include-controls>
          </insert-controls>
        </groups>
      </groups>
      <insert-controls>
        <include-controls>
          <with-ids>ctl_1.1</with-ids>
          <with-ids>ctl_1.2</with-ids>
        </include-controls>
      </insert-controls>
    </custom>
  </merge>

--show-stack-trace shows the following:

java.lang.UnsupportedOperationException: custom structuring
        at gov.nist.secauto.oscal.lib.profile.resolver.ProfileResolver.handleMerge(ProfileResolver.java:450) ~[gov.nist.secauto.oscal.liboscal-java-3.0.1.jar:?]
        at gov.nist.secauto.oscal.lib.profile.resolver.ProfileResolver.resolveProfile(ProfileResolver.java:205) ~[gov.nist.secauto.oscal.liboscal-java-3.0.1.jar:?]
        at gov.nist.secauto.oscal.lib.profile.resolver.ProfileResolver.resolve(ProfileResolver.java:234) ~[gov.nist.secauto.oscal.liboscal-java-3.0.1.jar:?]
        at gov.nist.secauto.oscal.lib.profile.resolver.ProfileResolver.resolve(ProfileResolver.java:219) ~[gov.nist.secauto.oscal.liboscal-java-3.0.1.jar:?]
        at gov.nist.secauto.oscal.tools.cli.core.commands.profile.ResolveSubcommand.executeCommand(ResolveSubcommand.java:287) ~[gov.nist.secauto.oscal.tools.oscal-cli.cli-core-1.0.1.jar:?]
        at gov.nist.secauto.metaschema.cli.processor.command.ICommandExecutor$1.execute(ICommandExecutor.java:48) ~[gov.nist.secauto.metaschema.cli-processor-0.12.1.jar:?]
        at gov.nist.secauto.metaschema.cli.processor.CLIProcessor$CallingContext.invokeCommand(CLIProcessor.java:403) ~[gov.nist.secauto.metaschema.cli-processor-0.12.1.jar:?]
        at gov.nist.secauto.metaschema.cli.processor.CLIProcessor$CallingContext.processCommand(CLIProcessor.java:374) [gov.nist.secauto.metaschema.cli-processor-0.12.1.jar:?]
        at gov.nist.secauto.metaschema.cli.processor.CLIProcessor.parseCommand(CLIProcessor.java:192) [gov.nist.secauto.metaschema.cli-processor-0.12.1.jar:?]
        at gov.nist.secauto.metaschema.cli.processor.CLIProcessor.process(CLIProcessor.java:176) [gov.nist.secauto.metaschema.cli-processor-0.12.1.jar:?]
        at gov.nist.secauto.oscal.tools.cli.core.CLI.runCli(CLI.java:78) [gov.nist.secauto.oscal.tools.oscal-cli.cli-core-1.0.1.jar:?]
        at gov.nist.secauto.oscal.tools.cli.core.CLI.main(CLI.java:55) [gov.nist.secauto.oscal.tools.oscal-cli.cli-core-1.0.1.jar:?]

Please assist.