code: public void migrate(File fromSource, File toDest) {
          IReaderHandler readerHandler = this;
          try (IDataMigratorReader reader = new JsonDataMigratorReader(fromSource);
               IDataMigratorWriter writer = new JsonDataMigratorWriter(toDest)) {
              this.writer = writer;
              reader.read(readerHandler);
          } catch (Exception e) {
              throw new RuntimeException(e);
          }
      }
docs: Migrate the data export file (fromSource) from whatever version it
  is to the latest apiman version format and write the result to a
  file (toDest).
  @param fromSource
  @param toDest