Types of occurrences of the entity type in the document. This
represents the number of instances of instances of an entity, not
number of mentions of an entity. For example, a bank statement may
only have one account_number, but this account number may be
mentioned in several places on the document. In this case the
'account_number' would be considered a REQUIRED_ONCE entity
type. If, on the other hand, we expect a bank statement to contain
the status of multiple different accounts for the customers, the
occurrence type will be set to REQUIRED_MULTIPLE.
Values:
OCCURRENCE_TYPE_UNSPECIFIED (0):
Unspecified occurrence type.
OPTIONAL_ONCE (1):
There will be zero or one instance of this
entity type. The same entity instance may be
mentioned multiple times.
OPTIONAL_MULTIPLE (2):
The entity type will appear zero or multiple
times.
REQUIRED_ONCE (3):
The entity type will only appear exactly
once. The same entity instance may be mentioned
multiple times.
REQUIRED_MULTIPLE (4):
The entity type will appear once or more
times.