question: sets the reference instant by default the system time when the streaming app is created . this instant with #expirebefore is used to calculate the #start and #end . concode_field_sep Duration bucketSpan concode_elem_sep PurgeListener purgeListener concode_elem_sep Duration expireBefore concode_elem_sep long bucketSpanMillis concode_elem_sep long start concode_elem_sep long fixedStart concode_elem_sep long lowestTimeBucket concode_elem_sep Instant referenceInstant concode_elem_sep WindowBoundedService windowBoundedService concode_elem_sep Runnable expiryTask concode_elem_sep boolean initialized concode_elem_sep long end concode_elem_sep Object lock concode_elem_sep int numBuckets concode_field_sep int getNumBuckets concode_elem_sep void setPurgeListener concode_elem_sep void run concode_elem_sep void endWindow concode_elem_sep Instant getReferenceInstant concode_elem_sep void setBucketSpan concode_elem_sep void beginWindow concode_elem_sep void setExpireBefore concode_elem_sep void setup concode_elem_sep long getTimeBucketFor concode_elem_sep void purgeTimeBucketsLessThanEqualTo concode_elem_sep void teardown concode_elem_sep Duration getBucketSpan concode_elem_sep Duration getExpireBefore
target: void function ( Instant arg0 ) { this . referenceInstant = arg0 ; }