Metadata API data structures

WIP:Metadata API

CRCE metadata API represents basic objects which are used and maintained inside of CRCE. Relations between those artefacts can be seen on this diagram:

All objects marked with label Entity extends Entity interface. Property, Capability, Requirement and Resource also implement EqualityComparable interface which enables deeper comparation.

• Resource - artifact which is uploaded, indexed and stored inside of CRCE
• Property - property of given Resource
• Capability - properties which are provided by given Resource
• Requirement - properties which are required by given Resource
• Attribute - represents one attribute of given metadata type
  • AttributeType - information about data type of Attribute
• Store - object which stores all metadatas
• MetadataFactory - object which provides creation of metadatas