'Returns an integer value from a v4 Property.
Args:
v4_property: an entity_v4_pb.Property
Returns:
an integer
Raises:
InvalidConversionError: if the property doesn\'t contain an integer value'

def __get_v4_integer_value(self, v4_property):

    check_conversion(v4_property.value().has_integer_value(), 'Property    does    not    contain    an    integer    value.')
    return v4_property.value().integer_value()
