docs: public void addSchema(String schemaURL) {
          try {
              schemaURL = URLDecoder.decode(schemaURL, "UTF-8");
          } catch (final UnsupportedEncodingException e) {
              e.printStackTrace();
              System.exit(-1);
          }
          assert(m_schemas.contains(schemaURL) == false);
          final File schemaFile = new File(schemaURL);
          assert(schemaFile != null);
          assert(schemaFile.isDirectory() == false);
          // this check below fails in some valid cases (like when the file is in a jar)
          //assert schemaFile.canRead()
          //    : "can't read file: " + schemaPath;
  
          m_schemas.add(schemaURL);
      }