docs: public static Object concat(Object[] arrs)
      {
          int   totalLen            = 0;
          Class commonComponentType = null;
          for (int i = 0, len = arrs.length; i < len; i++)
          {
              // skip all null arrays
              if (arrs[i] == null)
              {
                  continue;
              }
  
              int arrayLen = Array.getLength(arrs[i]);
  
              // skip all empty arrays
              if (arrayLen == 0)
              {
                  continue;
              }
  
              totalLen += arrayLen;
  
              Class componentType = arrs[i].getClass().getComponentType();
              commonComponentType =
                  (commonComponentType == null) ? componentType
                                                : commonClass(commonComponentType, componentType);
          }
  
          if (commonComponentType == null)
          {
              return null;
          }
  
          return concat(Array.newInstance(commonComponentType, totalLen), totalLen, arrs);
      }