The relevance threshold of the search results. The higher
relevance threshold is, the higher relevant results are shown
and the less number of results are returned.
Values:
RELEVANCE_THRESHOLD_UNSPECIFIED (0):
Default value. In this case, server behavior defaults to
RelevanceThreshold.HIGH.
HIGH (1):
High relevance threshold.
MEDIUM (2):
Medium relevance threshold.
LOW (3):
Low relevance threshold.
LOWEST (4):
Lowest relevance threshold.