[Registry-dev] Multi-value properties for resources

[Chathura C. Ekanayake]

I implemented the multi-value properties support for registry resources. 
Now a resource can have properties with one or more string values.
I did few changes to the Resource interface to expose this functionality 
in the API level.

Now properties attribute of resources contain string as the key and 
java.util.List of strings as the value.
Still we can use it for single value properties by using below methods.

void setProperty(String key, String value)
String getProperty(String key)

Above methods sets and gets the first element of the List and it appears 
to the user as setting and getting a single valued property.

Below two methods are provided to get multi-valued property functionality.

List getPropertyValues(String key) - returns the List of values 
associated with the property identified by the given key.
void addProperty(String key, String value) - adds the given value to the 
List of values associated with the property identified by the given key.

As Deepal has implemented APP support for this, multi-valued properties 
functionality is available to the APP interface as well.
We will be adding this functionality to the registry UI soon.

Thanks,
Chathura