docs: protected byte[] getGZipData() throws SQLException {
  
          byte[] bytes = gZipData();
  
          if (bytes != null) {
              return bytes;
          }
  
          if ((this.outputStream == null) || !this.outputStream.isClosed()
                  || this.outputStream.isFreed()) {
              throw Exceptions.notReadable();
          }
  
          try {
              setGZipData(this.outputStream.toByteArray());
  
              return gZipData();
          } catch (IOException ex) {
              throw Exceptions.notReadable();
          } finally {
              this.freeOutputStream();
          }
      }