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

Appendable.class,
        StringBuilder.class,
        StringBuffer.class,
        Throwable.class,
        Exception.class);
  }
  public void testGet_io() throws IOException {
    assertEquals(-1, ArbitraryInstances.get(InputStream.class).read());
    assertEquals(-1, ArbitraryInstances.get(ByteArrayInputStream.class).read());
    assertEquals(-1, ArbitraryInstances.get(Readable.class).read(CharBuffer.allocate(1)));
    assertEquals(-1, ArbitraryInstances.get(Reader.class).read());
    assertEquals(-1, ArbitraryInstances.get(StringReader.class).read());
    assertEquals(0, ArbitraryInstances.get(Buffer.class).capacity());
    assertEquals(0, ArbitraryInstances.get(CharBuffer.class).capacity());
    assertEquals(0, ArbitraryInstances.get(ByteBuffer.class).capacity());
    assertEquals(0, ArbitraryInstances.get(ShortBuffer.class).capacity());
    assertEquals(0, ArbitraryInstances.get(IntBuffer.class).capacity());
    assertEquals(0, ArbitraryInstances.get(LongBuffer.class).capacity());
    assertEquals(0, ArbitraryInstances.get(FloatBuffer.class).capacity());
    assertEquals(0, ArbitraryInstances.get(DoubleBuffer.class).capacity());
    ArbitraryInstances.get(PrintStream.class).println("test");
    ArbitraryInstances.get(PrintWriter.class).println("test");
    assertNotNull(ArbitraryInstances.get(File.class));
    assertFreshInstanceReturned(
        ByteArrayOutputStream.class, OutputStream.class,
        Writer.class, StringWriter.class,
        PrintStream.class, PrintWriter.class);
    assertEquals(ByteSource.empty(), ArbitraryInstances.get(ByteSource.class));
    assertEquals(CharSource.empty(), ArbitraryInstances.get(CharSource.class));
    assertNotNull(ArbitraryInstances.get(ByteSink.class));