Raising descriptive exception upon natural id look-ups which are not supported yet
OGM-548 Update AssociationKey javadoc
OGM-548 Remove methods from AssociationKey that delegate to metadata
OGM-548 Add AssociationContext as parameter for GridDialect#createTupleAssociation(...)
OGM-548 Remove redundant properties from relationship in Neo4j:

  * Remove foreign key properties from embedded nodes
  * Store only index columns in relationships
  * Remove TEMP nodes
  * Add relationhip for unidirectional *ToOne associations (in
    preparation of OGM-521)
  * Add fields to AssociationContext
OGM-548 Update Neo4j mapping unit tests

  * Relationships should not have properties except for indexes
  * Test fail for unexpected properties
  * Remove redundant columns for embedded associations
OGM-548 Add test to check the mapping of @ElementCollection with index in Neo4j
OGM-548 Add test to check the mapping of Maps in Neo4j
OGM-548 Add GraphLogger class to log information about graph elements
OGM-548 Log details of created/updated graph elements
OGM-548 Update Neo4j documentation
OGM-548 Remove AssociationKey#targetKey
OGM-548 Clean up Neo4jJpaTestCase
OGM-548 Add ArrayHelper#EMPTY_STRING_ARRAY
OGM-548 Remove additional constructor in AssociationKeyMetadata
OGM-548 Additional javadoc for AssociationKeyMetadata#getRowKeyIndexColumnNames
OGM-548 Add ArrayHelper#indexOf
OGM-548 Add the target key of an association in the RowKey
OGM-548 Fix AssociationContext creation in AssociationPersister
OGM-548 Remove AssociationContext where it is not required