Can we alter MarkupBuilder to ignore optional attributes that aren't specified (contain null values). Currently MarkupBuilder throws a NullPointerException if I create a node using attributes that contain a null map value. For example: def writer = new StringWriter() def builder = new MarkupBuilder(writer) builder.A { B { C(D: 'E', F: null) { } } } // throws NullPointerException in MarkupBuilder.createNode When building XML using MarkupBuilder, I find it useful to specify all attributes (required or optional) for a node in one line rather than having to implement ugly logic checks myself like follows: builder.A { B { def map = [:] if (E) { map['D'] = 'E' } if (F) { map['F'] = 'G' } C(map) { } } }