driver-core/src/main/com/mongodb/ReadPreference.java
public static TaggableReadPreference nearest(final TagSet tagSet,
                                                 final long maxStaleness, final TimeUnit timeUnit) {
        return new NearestReadPreference(singletonList(tagSet), maxStaleness, timeUnit);
    }
public static TaggableReadPreference nearest(final TagSet tagSet,
                                                 final long maxStaleness, final TimeUnit timeUnit) {
        return new NearestReadPreference(singletonList(tagSet), maxStaleness, timeUnit);
    }
public static TaggableReadPreference nearest ( final TagSet tagSet , final long maxStaleness , final TimeUnit timeUnit ) { return new NearestReadPreference ( singletonList ( tagSet ) , maxStaleness , timeUnit ) ; }
Gets a read preference that forces reads to the primary or a secondary with the given set of tags that is less stale than the
given maximum.

<p>
The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses,
and selects only those secondaries whose staleness is less than or equal to maxStaleness.
</p>

@param tagSet the set of tags to limit the list of secondaries to
@param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency
plus 10 seconds, whichever is greatest.
@param timeUnit the time unit of maxStaleness
@return ReadPreference which reads nearest node respective of tags.
@since 3.4
@see TaggableReadPreference#getMaxStaleness(TimeUnit)
Gets a read preference that forces reads to the primary or a secondary with the given set of tags that is less stale than the given maximum .