final class TestStream extends OutputStream {  
  private final OutputStream delegate;  
  TestStream(OutputStream delegate) {
    this.delegate = delegate
  }  
  public void write(int b) throws IOException {
    delegate.write(b);
  }  
  public void write(byte[] b) throws IOException {
    delegate.write(b);
  }  
  public void write(byte[] b, int off, int len) throws IOException {
    delegate.write(b, off, len);
  }  
  public void flush() throws IOException {
    delegate.flush();
  }  
   public void close() throws IOException {
    delegate.close();
  }
}
class TestFilter extends ConsoleLogFilter  {     
    @Override
    public OutputStream decorateLogger(AbstractBuild build, OutputStream logger)
            throws IOException, InterruptedException {
        if (logger == null) {
            return null;
        }
     
        return new TestStream(logger)
    }
}
ConsoleLogFilter subsequent = new TestFilter();
ConsoleLogFilter original = getContext(ConsoleLogFilter.class);
println original //prints null
timestamps {
    original = getContext(ConsoleLogFilter.class);
    println original //prints  TimestampNotesConsoleLogFilter object
    echo "Out of Context" //Visible
    withContext(BodyInvoker.mergeConsoleLogFilters(original, subsequent)) {
        echo "In context " //Not visible
    }
    withContext(new TestFilter()) {
        echo "In context " //Not visible
    }
}

Started by user jenkins
Running in Durability level: PERFORMANCE_OPTIMIZED
[Pipeline] getContext
[Pipeline] echo
null
[Pipeline] timestamps
[Pipeline] {
[Pipeline] getContext
[Pipeline] echo
07:22:58 hudson.plugins.timestamper.pipeline.TimestamperStep$TimestampNotesConsoleLogFilter@1d678d7a
[Pipeline] echo
07:22:58 Out of Context
[Pipeline] withContext
[Pipeline] {
[Pipeline] echo
[Pipeline] }
[Pipeline] // withContext
[Pipeline] withContext
[Pipeline] {
[Pipeline] echo
[Pipeline] }
[Pipeline] // withContext
[Pipeline] }
[Pipeline] // timestamps
[Pipeline] End of Pipeline
Finished: SUCCESS