Holds properties that are placed inside SpaceDocument

Represents a document which can be stored and retrieved from the space. A document is a collection of properties (which are name-value pairs) associated with a type. A property name is a string. A property value can be of any type, but it is usually either a scalar (e.g. int, String, Date, etc.), a set of properties IDictionary<(Of <(<'TKey, TValue>)>)>, or an array/collection or scalars or maps. Documents of the same type can have different properties, which provides more dynamic schema than concrete types. SpaceTypeDescriptorBuilderISpaceTypeDescriptor