code: public boolean checkViewable(CmsObject cms, String referenceUri) {
  
          try {
              CmsExplorerTypeSettings settings = OpenCms.getWorkplaceManager().getExplorerTypeSetting(m_typeName);
              CmsResource referenceResource = cms.readResource(referenceUri);
              if (settings == null) {
                  // no explorer type
                  return false;
              }
              return settings.getAccess().getPermissions(cms, referenceResource).requiresViewPermission();
          } catch (CmsException e) {
              LOG.error(e.getLocalizedMessage(), e);
              return false;
          }
      }
docs: Checks if a resource type is viewable for the current user.
  If not, this resource type should not be available at all within the ADE 'add-wizard'.<p>
  
  @param cms the current CMS context
  @param referenceUri the resource URI to check permissions for
  
  @return <code>true</code> if the resource type is viewable