code: public void checkResources() throws InstallException {
          getResolveDirector().checkResources();
          if (installAssets != null) {
              for (List<InstallAsset> iaList : installAssets) {
                  for (InstallAsset ia : iaList) {
                      checkResource(ia);
                  }
              }
          }
  
          long required = getResolveDirector().getInstallResourcesMainAttachmentSize();
          String requiredSpace = castToPrintableMessage(required);
          logger.log(Level.FINEST, "Total required space for installation is " + requiredSpace + " including temporary files.");
          File wlpDir = product.getInstallDir();
          long free = wlpDir.getFreeSpace();
          String wlpDirSpace = castToPrintableMessage(wlpDir.getFreeSpace());
          logger.log(Level.FINEST, "Total available space is " + wlpDirSpace + ".");
          if (free < required) {
              try {
                  throw ExceptionUtils.createByKey("ERROR_WLP_DIR_NO_SPACE", wlpDir.getCanonicalPath(), wlpDirSpace, requiredSpace);
              } catch (IOException e) {
                  throw ExceptionUtils.create(e);
              }
          }
      }
docs: Checks if resources in installAssets are already installed and
  if there is enough space in the install directory to install
  
  @throws InstallException