question: private ManifestModInfo registerMod ( File file , Manifest manifest ) { ManifestModInfo mod = loadMod ( file , manifest ) ; if ( mod != null ) { if ( idMap . containsKey ( mod . getModID ( ) ) ) { ModInfo mod2 = idMap . get ( mod . getModID ( ) ) ; duplicates . put ( mod . getModID ( ) , mod ) ; duplicates . put ( mod . getModID ( ) , mod2 ) ; log . error ( "Duplicate mod IDs for files '%s' and '%s'" , mod . getModFile ( ) , mod2 . getModFile ( ) ) ; } else { modList . add ( mod ) ; idMap . put ( mod . getModID ( ) , mod ) ; } } return mod ; }
target:  Constructs and registers a mod.