code: public Date modifyDatastreamByValue(Context context,
                                          String pid,
                                          String datastreamID,
                                          String[] altIDs,
                                          String dsLabel,
                                          String mimeType,
                                          String formatURI,
                                          InputStream dsContent,
                                          String checksumType,
                                          String checksum,
                                          String logMessage,
                                          Date lastModifiedDate) throws ServerException {
          try {
              CreatorJournalEntry cje =
                      new CreatorJournalEntry(METHOD_MODIFY_DATASTREAM_BY_VALUE,
                                              context);
              cje.addArgument(ARGUMENT_NAME_PID, pid);
              cje.addArgument(ARGUMENT_NAME_DS_ID, datastreamID);
              cje.addArgument(ARGUMENT_NAME_ALT_IDS, altIDs);
              cje.addArgument(ARGUMENT_NAME_DS_LABEL, dsLabel);
              cje.addArgument(ARGUMENT_NAME_MIME_TYPE, mimeType);
              cje.addArgument(ARGUMENT_NAME_FORMAT_URI, formatURI);
              cje.addArgument(ARGUMENT_NAME_DS_CONTENT, dsContent);
              cje.addArgument(ARGUMENT_NAME_CHECKSUM_TYPE, checksumType);
              cje.addArgument(ARGUMENT_NAME_CHECKSUM, checksum);
              cje.addArgument(ARGUMENT_NAME_LOG_MESSAGE, logMessage);
              cje.addArgument(ARGUMENT_NAME_LAST_MODIFIED_DATE, lastModifiedDate);
              return (Date) cje.invokeAndClose(delegate, writer);
          } catch (JournalException e) {
              throw new GeneralException("Problem creating the Journal", e);
          }
      }
docs: Create a journal entry, add the arguments, and invoke the method.