*/
class DefaultBuilderProblem implements BuilderProblem {
    final String source;
    final int lineNumber;
    final int columnNumber;
    final Exception exception;
    final String message;
    final Severity severity;

    DefaultBuilderProblem(
            String source, int lineNumber, int columnNumber, Exception exception, String message, Severity severity) {
        this.source = source;

    }

    static class GavCacheKey {

        private final String gav;

        private final String tag;

        private final int hash;

        GavCacheKey(String groupId, String artifactId, String version, String tag) {
            this(gav(groupId, artifactId, version), tag);
        }

        GavCacheKey(String gav, String tag) {

        return null;
    }

    @Override
    public boolean equals(Object o) {
        return this == o || o instanceof PathSource ps && Objects.equals(path, ps.path);
    }

    @Override
    public int hashCode() {
        return Objects.hash(path);
    }

    @Override
    public String toString() {
        return "PathSource[" + "location='" + location + '\'' + ", " + "path=" + path + ']';
    }

  }

  /**
   * This atrocity is here to let us report several of the elements in the stream if there were more
   * than one, not just two.
   */
  private static final class ToOptionalState {
    static final int MAX_EXTRAS = 4;

    @CheckForNull Object element;
    List<Object> extras;

    ToOptionalState() {
      element = null;
      extras = emptyList();
    }