title: Doxygen: grouping classes in several nested groups
body: <p>I intend to include some documented C++ classes (let say <code>AClass</code>) within a Doxygen group (let say <code>GROUP_C</code>), while that group is into another one (let say <code>GROUP_B</code>), and that second group into another, base one (let say <code>GROUP_A</code>). Like this:</p>
  
  <pre><code>/** \addtogroup GROUP_A */
  /** @{ */
  
  /** \defgroup GROUP_B */
  /** @{ */
  
  /** \defgroup GROUP_C */
  /** @{ */
  
  /// Comment
  class AClass
  {
  };
  
  /** @} */
  
  /** @} */ 
  /** @} */
  </code></pre>
  
  <p>I'm trying to get a clean and logical documentation for that situation, but, as simple as I see it, I have not been able to found anything more specific than the Doxygen official documentation, where nothing is said about any cyclical grouping problems. However, just doxygen-ing the simple code above, such problems occur:</p>
  
  <pre><code>warning: Refusing to add group GROUP_C to group GROUP_B, since the latter is already a subgroup of the former
  </code></pre>
  
  <p>I also get strange breadcrumbs indications of the generated module under the <code>AClass</code> documentation:</p>
  
  <p><a href="https://i.stack.imgur.com/K6Uph.png" rel="nofollow"><img src="https://i.stack.imgur.com/K6Uph.png" alt="enter image description here"></a></p>
  
  <p>Does anybody know what am I understanding wrong in the nesting-group system of Doxygen?</p>
  
  <p>Thanks in advance!</p>