code: public boolean updateSchema(String text, ContentType contentType) {
          Utils.require(text != null && text.length() > 0, "text");
          Utils.require(contentType != null, "contentType");
          
          try {
              // Send a PUT request to "/_applications/{application}".
              byte[] body = Utils.toBytes(text);
              StringBuilder uri = new StringBuilder("/_applications/");
              uri.append(Utils.urlEncode(m_appDef.getAppName()));
              RESTResponse response =
                  m_restClient.sendRequest(HttpMethod.PUT, uri.toString(), contentType, body);
              m_logger.debug("updateSchema() response: {}", response.toString());
              throwIfErrorResponse(response);
              return true;
          } catch (Exception e) {
              throw new RuntimeException(e);
          }
      }
docs: Update the schema for this session's application with the given definition. The
  text must be formatted in XML or JSON, as defined by the given content type. True
  is returned if the update was successful. An exception is thrown if an error
  occurred.
  
  @param text          Text of updated schema definition.
  @param contentType   Format of text. Must be {@link ContentType#APPLICATION_JSON} or
  {@link ContentType#TEXT_XML}.
  @return              True if the schema update was successful.