Binding failure with cloned arrays

[snicoll]

This sample reproduces the issue raised on SO.

Binding works fine if the array isn't cloned and breaks when it is.

[mbhave]

If there is a bound value, the AggregateBinder tries to get the existing value so that it can merge that with the bound value. The getter in the sample throws a NPE since this.urls is null.

For Array types the merge just returns the bound value so getting the existing value is unnecessary. Maybe if we skip this get for Array types this will work.