public boolean hasNonNullDefault() {
        DefaultTrait defaultTrait = getTrait(DefaultTrait.class).orElse(null);
        return defaultTrait != null && !defaultTrait.toNode().isNullNode();
    }
@return Returns true if the member has a default not set to null.
smithy-model/src/main/java/software/amazon/smithy/model/shapes/MemberShape.java