line 227 results in NPE if the other object does not contain the specified key.

Object a = get( key );
Object b = other.get( key );

if ( a instanceof Number && b instanceof Number )

{ if ( ((Number)a).doubleValue() != ((Number)b).doubleValue() ) return false; }

else

{ HERE (b=null) ----> if ( ! a.equals( b ) ) return false; }