code: public void setCustomPlugins(Map<String, Boolean> customPlugins) {
          if (customPlugins == null) {
              throw new IllegalArgumentException("customPlugins may not be null.");
          }
          this.customPlugins = customPlugins;
      }
docs: Additional plugins which could be used by {@link IFindBugsEngine} (if
  enabled), or which shouldn't be used (if disabled). If a plugin is not
  included in the set, it's enablement depends on it's default settings.
  
  @param customPlugins
  map with additional third party plugin locations (as absolute
  paths), never null, but might be empty
  @see Plugin#isCorePlugin()
  @see Plugin#isGloballyEnabled()