This is the work horse type and represents an object with one or more field values that can be retrieved
by the graphql system.
Those fields can themselves by object types and so on until you reach the leaf nodes of the type tree represented
See http://graphql.org/learn/schema/#object-types-and-fields for more details on the concept.
This returns GraphQLInterface or GraphQLTypeReference instances, if the type
references are not resolved yet. After they are resolved it contains only GraphQLInterface.
Reference resolving happens when a full schema is built.