Please get checker-qual and error_prone_annotations to agree with caffeine...update your check-qual dependency to 2.6.0 and your error_prone_annotations dependency to 2.3.3, please.

    Require upper bound dependencies error for org.checkerframework:checker-qua>
        +-com.google.guava:guava:27.1-jre (managed) <-- com.google.guava:guava:>
          +-org.checkerframework:checker-qual:2.5.2
    and
        +-com.github.ben-manes.caffeine:caffeine:2.7.0
          +-org.checkerframework:checker-qual:2.6.0

    Require upper bound dependencies error for com.google.errorprone:error_pron>
        +-com.google.guava:guava:27.1-jre (managed) <-- com.google.guava:guava:>
          +-com.google.errorprone:error_prone_annotations:2.2.0
    and
        +-com.github.ben-manes.caffeine:caffeine:2.7.0
          +-com.google.errorprone:error_prone_annotations:2.3.3

private static final NullByteSink INSTANCE = new NullByteSink();
    @Override
    public OutputStream openStream() {
      return ByteStreams.nullOutputStream();
    }
  }
  // 
  // 
  // 
  @SuppressWarnings("ComparableType")
  private static final class ByToString implements Comparable<Object>, Serializable {
    private static final ByToString INSTANCE = new ByToString();
    @Override
    public int compareTo(Object o) {
      return toString().compareTo(o.toString());
    }
    @Override
    public String toString() {
      return "BY_TO_STRING";
    }
    private Object readResolve() {
      return INSTANCE;
    }
  }
  // 
  private static final class AlwaysEqual extends Ordering<Object> implements Serializable {