Fix for internalGetAttachments, ExtendedProperty, MapiTypeConverterMapEntry

In ExchangeService, method internalGetAttachments:
List propsArray = new ArrayList();
for (PropertyDefinitionBase propertyDefinitionBase :
additionalProperties)

If addtionalProperties is null (and it can be), this throws a
NullPointerException.
A check for null is done here:
if (additionalProperties != null) {
request.getAdditionalProperties().addAll(propsArray);
}

This check should be done earlier.

And

propsArray.add(additionalProperties);

This will result in adding a list to another list and later on result in
a ClassCastException.

It should be:
for (PropertyDefinitionBase propertyDefinitionBase :
additionalProperties)
{
propsArray.add(propertyDefinitionBase);
}
Should we check the type for all the elements?