private final BiPredicate<? super R, ? super R> equivalence;

  private CollectorTester(
      Collector<T, A, R> collector, BiPredicate<? super R, ? super R> equivalence) {
    this.collector = checkNotNull(collector);
    this.equivalence = checkNotNull(equivalence);
  }

  /**
   * Different orderings for combining the elements of an input array, which must all produce the
   * same result.
   */

   * collector without breaking j2cl?
   */
  private static final Collector<Object, ?, Optional<Object>> TO_OPTIONAL =
      Collector.of(
          ToOptionalState::new,
          ToOptionalState::add,
          ToOptionalState::combine,
          ToOptionalState::getOptional,
          Collector.Characteristics.UNORDERED);

  /**

        collector.setSource("SOURCE_PROBLEM2");
        collector.add(null, "PROBLEM2", -1, -1, null);

        collector.setSource("SOURCE_PROBLEM3");
        collector.add(null, "PROBLEM3", -1, -1, null);

        assertEquals("", collector.getProblems().get(0).getSource());
        assertEquals("SOURCE_PROBLEM2", collector.getProblems().get(1).getSource());

     */
    @Override
    public TransformerContext initialize(ModelBuildingRequest request, ModelProblemCollector collector) {
        // We must assume the TransformerContext was created using this.newTransformerContextBuilder()
        DefaultModelProblemCollector problems = (DefaultModelProblemCollector) collector;
        return new TransformerContext() {

            @Override
            public Path locate(Path path) {

        this.mechanism = mechanism;
    }


    @Override
    public byte[] toByteArray () {
        try {
            ByteArrayOutputStream collector = new ByteArrayOutputStream();
            ASN1OutputStream der = ASN1OutputStream.create(collector, ASN1Encoding.DER);
            ASN1EncodableVector fields = new ASN1EncodableVector();
            int res = getResult();
            if ( res != UNSPECIFIED_RESULT ) {

        new LineProcessor<List<String>>() {
          List<String> collector = new ArrayList<>();

          @Override
          public boolean processLine(String line) {
            collector.add(whitespace().trimFrom(line));
            return true;
          }

          @Override
          public List<String> getResult() {
            return collector;
          }
        };

        ProblemCollector collector = ProblemCollectorFactory.newInstance(null);
        problems.forEach(p -> collector.add(
                Problem.Severity.valueOf(p.getSeverity().name()),
                p.getMessage(),
                p.getLineNumber(),
                p.getColumnNumber(),
                p.getException()));
        return collector.getProblems();
    }

        new LineProcessor<List<String>>() {
          List<String> collector = new ArrayList<>();

          @Override
          public boolean processLine(String line) {
            collector.add(whitespace().trimFrom(line));
            return true;
          }

          @Override
          public List<String> getResult() {
            return collector;
          }
        };

of this functionality is to improve efficiency: manually freeing memory
before a garbage collection delays that cycle. Less frequent cycles means
the CPU cost of the garbage collector is incurred less frequently.

This functionality in this package is mostly captured in the Arena type.
Arenas allocate large chunks of memory for Go values, so they're likely to

            ByteArrayOutputStream collector = new ByteArrayOutputStream();
            ASN1OutputStream der = ASN1OutputStream.create(collector, ASN1Encoding.DER);
            DERTaggedObject derApplicationSpecific = new DERTaggedObject(false, BERTags.APPLICATION, 0, new DERSequence(ev));
            der.writeObject(derApplicationSpecific);
            return collector.toByteArray();
        }
        catch ( IOException ex ) {