code: public void setContextCenter(Pattern pattern) {
  	// build up the classgraph printing the relations for all of the
  	// classes that make up the "center" of this context
  	this.pattern = pattern;
  	matched = new ArrayList<ClassDoc>();
  	for (ClassDoc cd : root.classes()) {
  	    if (pattern.matcher(cd.toString()).matches()) {
  		matched.add(cd);
  		addToGraph(cd);
  	    }
  	}
      }
docs: Can be used to setup a different pattern for this context matcher.
  <p>
  This can be used to speed up subsequent matching with the same global
  options, since the class network informations will be reused.
  @param pattern