anchor.diff:  NOTE: When both global debugging and local `checkpoint()` are enabled, checkpointed
   snapshot stacks are appended as suppressed error output after the observing operator
   graph and following the same declarative order.
  +
  +[[reactor-tools-debug]]
  +== Production-ready Global Debugging
  +Project Reactor comes with a separate Java Agent that instruments your code and adds
  +debugging info without paying the cost of capturing the stacktrace on every operator call.
  +The behaviour is very similar to <<debug-activate>>, but without the runtime performance overhead.
  +
  +To use it in your app, you must add it as a dependency.
  +
  +The following example shows how to add `reactor-tools` as a dependency in Maven:
  +
  +.reactor-tools in Maven, in `<dependencies>`
  +====
  +[source,xml]
  +----
  +<dependency>
  +    <groupId>io.projectreactor</groupId>
  +    <artifactId>reactor-tools</artifactId>
  +    <1>
  +</dependency>
  +----
  +<1> If you use the <<getting,BOM>>, you do not need to specify a `<version>`.
  +====
  +
  +The following example shows how to add `reactor-tools` as a dependency in Gradle:
  +
  +.reactor-tools in Gradle, amend the `dependencies` block
  +====
  +[source,groovy]
  +----
  +dependencies {
  +   compile 'io.projectreactor:reactor-tools'
  +}
  +----
  +====
  +
  +It also needs to be explicitly initialized with:
  +====
  +[source,java]
  +----
  +ReactorDebugAgent.init();
  +----
  +====
  +
  +TIP: Since the implementation will instrument your classes when they are loaded,
  +the best place to put it is before everything else in your main(String[]) methood:
  +====
  +[source,java]
  +----
  +public static void main(String[] args) {
  +    ReactorDebugAgent.init();
  +    SpringApplication.run(Application.class, args);
  +}
  +----
  +====
  +
  +You may also re-process existing classes if you cannot run the init eagerly (e.g. in the tests):
  +====
  +[source,java]
  +----
  +ReactorDebugAgent.init();
  +ReactorDebugAgent.processExistingClasses();
  +----
  +====
  +
  +WARNING: Be aware that the re-processing takes a couple of seconds due to the need to iterate over
  +all loaded classes and apply the transformation.
  +Use it only if you see that some call-sites are not instrumented.
  +
  +=== Limitations
  +`ReactorDebugAgent` is implemented as a Java Agent and uses https://bytebuddy.net/#/[ByteBuddy]
  +to perform the self-attach.
  +Self-attach may not work on some JVMs, please refer to ByteBuddy's documentation for more details.
   
   == Logging a Sequence
   
  
positive.code: [[debug-activate]]
  == Activating Debug Mode
  
  Even though the stacktrace was still able to convey some information for someone with a
  bit of experience, we can see that it is not ideal by itself in more advanced cases.
  
  
negative.code: is why this debugging feature should only be activated in a controlled manner, as a last
  resort.
  
  [[checkpoint-alternative]]
  === The `checkpoint()` Alternative
  
  The debug mode is global and affects every single operator assembled into a `Flux` or a
  