public default <Type> Collection<Type> getPropertyCollection(
            GuacamoleProperty<Type> property, Type defaultValue)
            throws GuacamoleException {
        return new DefaultEnvironment(this).getPropertyCollection(property, defaultValue);
    }
Given a GuacamoleProperty, parses and returns the value set for that
property in guacamole.properties, if any. If no value is found, a
Collection is returned with the provided default value. The
implementation of parsing and returning a collection of multiple
values is up to the individual property implementations, and not all
implementations will support reading and returning multiple values.

@param <Type>
    The type that the given property is parsed into.

@param property
    The property to read from guacamole.properties.

@param defaultValue
    The single value to return in the Collection if no value was given
    in guacamole.properties.

@return
    A sorted collection of the the parsed values of the property as read
    from guacamole.properties, or a Collection with the single default
    value provided.

@throws GuacamoleException
    If an error occurs while parsing the value for the given property in
    guacamole.properties.
guacamole-ext/src/main/java/org/apache/guacamole/environment/Environment.java