code: void addClassInfo(final ClassInfo classInfo) {
          if (memberClassNameToClassInfo == null) {
              memberClassNameToClassInfo = new HashMap<>();
          }
          memberClassNameToClassInfo.put(classInfo.getName(), classInfo);
      }
docs: Merge a {@link ClassInfo} object for a package-info.class file into this PackageInfo. (The same
  package-info.class file may be present in multiple definitions of the package in different modules.)
  
  @param classInfo
  the {@link ClassInfo} object to add to the package.