question: public static synchronized void registerStream ( Stream stream ) { if ( STREAMS . containsKey ( stream . getName ( ) ) ) { throw new IllegalArgumentException ( "Can't register stream with name [" + stream . getName ( ) + "] more than once" ) ; } HashMap < String , Stream > map = new HashMap < > ( ) ; map . putAll ( STREAMS ) ; map . put ( stream . getName ( ) , stream ) ; STREAMS = Collections . unmodifiableMap ( map ) ; }
target:  Registers the given stream and associate it with the given types.