According to the Brooklyn Eagle, an annual Falun Gong conference was "expected to bring upwards of 9,000 practitioners from around the world to Barclays Center."
The May event calendar for the community, belatedly released Tuesday night, simply mentioned a "private event," without details.
(Could it be the sensitivity to publicizing an organization in conflict with the Chinese government, given that Atlantic Yards/Pacific Park majority owner Greenland Group is significantly owned by the government of Shanghai? A resident reports that a pedestrian manager from Sam Schwartz Engineering said, after consulting a document, that the event was for the "Eastern U.S. Buddhist Studies Association," which I have not been able to find listed as an alternate name.)
It's unclear why the calendar wasn't released before the month began, but the delay did allow the arena to mention--in the preliminary calendars for future months, below--the recently announced Barbra Streisand concerts in August.
In May 2016, the arena has six concerts, four graduations, one comedy event, and one "private event," aka that Falun Gong conference. The largest events have already passed: Justin Bieber concerts. But this weekend should be busy with the Bad Boy Reunion concerts.
The May 2015 calendar
Current calendars for June, July and August
These surely will be augmented. Note two graduations in June, as well as the NBA draft.
Note the Hillsong church conference in August, as well as the Streisand concerts.
In March and April
I neglected to publish the March 2016 and April 2016 calendars.