code: public EnvironmentConfig setGcFilesInterval(final int files) throws InvalidSettingException {
          if (files < 1) {
              throw new InvalidSettingException("Invalid number of files: " + files);
          }
          return setSetting(GC_FILES_INTERVAL, files);
      }
docs: Sets the number of new {@code Log} files (.xd files) that must be created to trigger if necessary (if database
  utilization is not sufficient) the next background cleaning cycle (single run of the database garbage collector)
  after the previous cycle finished. Default value is {@code 3}, i.e. GC can start after each 3 newly created
  {@code Log} files. Cannot be less than {@code 1}.
  <p>Mutable at runtime: yes
  
  @param files number of new .xd files that must be created to trigger the next background cleaning cycle
  @return this {@code EnvironmentConfig} instance
  @throws InvalidSettingException {@code files} is less than {@code 1}