code: public I_CmsPrincipal lookupPrincipal(CmsRequestContext context, String principalName) {
  
          CmsDbContext dbc = m_dbContextFactory.getDbContext(context);
          I_CmsPrincipal result = null;
          try {
              result = m_driverManager.lookupPrincipal(dbc, CmsOrganizationalUnit.removeLeadingSeparator(principalName));
          } finally {
              dbc.clear();
          }
          return result;
      }
docs: Lookup and read the user or group with the given name.<p>
  
  @param context the current request context
  @param principalName the name of the principal to lookup
  
  @return the principal (group or user) if found, otherwise <code>null</code>