question: public void makeImmutable ( ) { if ( isMutable ) { if ( assertions != null ) { int length = assertions . size ( ) ; for ( int i = 0 ; i < length ; i ++ ) { Assertion assertion = ( Assertion ) assertions . get ( i ) ; assertion . makeImmutable ( ) ; } assertions = Collections . unmodifiableList ( assertions ) ; } if ( encryptedAssertions != null ) { encryptedAssertions = Collections . unmodifiableList ( encryptedAssertions ) ; } if ( assertionIDRefs != null ) { int length = assertionIDRefs . size ( ) ; for ( int i = 0 ; i < length ; i ++ ) { AssertionIDRef assertionIDRef = ( AssertionIDRef ) assertionIDRefs . get ( i ) ; assertionIDRef . makeImmutable ( ) ; } assertionIDRefs = Collections . unmodifiableList ( assertionIDRefs ) ; } if ( assertionURIRefs != null ) { assertionURIRefs = Collections . unmodifiableList ( assertionURIRefs ) ; } if ( additionalInfo != null ) { additionalInfo = Collections . unmodifiableList ( additionalInfo ) ; } isMutable = false ; } }
target:  Makes the object immutable