code: @Path("/{dsID}")
      @PUT
      public Response modifyDatastream(@PathParam(RestParam.PID) String pid,
                                       @PathParam(RestParam.DSID) String dsID,
                                       @QueryParam(RestParam.DS_LOCATION) String dsLocation,
                                       @QueryParam(RestParam.ALT_IDS) List<String> altIDs,
                                       @QueryParam(RestParam.DS_LABEL) String dsLabel,
                                       @QueryParam(RestParam.VERSIONABLE) Boolean versionable,
                                       @QueryParam(RestParam.DS_STATE) String dsState,
                                       @QueryParam(RestParam.FORMAT_URI) String formatURI,
                                       @QueryParam(RestParam.CHECKSUM_TYPE) String checksumType,
                                       @QueryParam(RestParam.CHECKSUM) String checksum,
                                       @QueryParam(RestParam.MIME_TYPE) String mimeType,
                                       @QueryParam(RestParam.LOG_MESSAGE) String logMessage,
                                       @QueryParam(RestParam.IGNORE_CONTENT) @DefaultValue("false") boolean ignoreContent,
                                       @QueryParam(RestParam.LAST_MODIFIED_DATE) DateTimeParam lastModifiedDate,
                                       @QueryParam(RestParam.FLASH) @DefaultValue("false") boolean flash) {
          return addOrUpdateDatastream(false,
                                       pid,
                                       dsID,
                                       m_headers.getMediaType(),
                                       mimeType,
                                       null,
                                       dsLocation,
                                       altIDs,
                                       dsLabel,
                                       versionable,
                                       dsState,
                                       formatURI,
                                       checksumType,
                                       checksum,
                                       logMessage,
                                       ignoreContent,
                                       lastModifiedDate,
                                       flash);
      }
docs: <p>Modify an existing datastream.
  </p><p>
  PUT /objects/{pid}/datastreams/{dsID} ? dsLocation altIDs dsLabel
  versionable dsState formatURI checksumType checksum logMessage
  </p><p>
  Successful Response: Status: 200 OK Content-Type: text/xml Body: XML
  datastream profile</p>