Specifies when to overwrite an object in the sink when an
object with matching name is found in the source.
Values:
OVERWRITE_WHEN_UNSPECIFIED (0):
Overwrite behavior is unspecified.
DIFFERENT (1):
Overwrites destination objects with the
source objects, only if the objects have the
same name but different HTTP ETags or checksum
values.
NEVER (2):
Never overwrites a destination object if a
source object has the same name. In this case,
the source object is not transferred.
ALWAYS (3):
Always overwrite the destination object with
the source object, even if the HTTP Etags or
checksum values are the same.
