In crash reports, the "CPU" is "bcw$7@<memory address>"

In the last line of a crash report, it shows your CPU. In 16w21a however, it shows a raw Java object and not a string:

CPU: bcw$7@74f1c9b9

Here's a full crash report:

Crash report

---- Minecraft Crash Report ----
// I let you down. Sorry :(

Time: 25/05/16 4:26 PM
Description: Manually triggered debug crash

java.lang.Throwable
	at bcw.az(SourceFile:1701)
	at bcw.t(SourceFile:1622)
	at bcw.av(SourceFile:964)
	at bcw.a(SourceFile:392)
	at net.minecraft.client.main.Main.main(SourceFile:124)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Thread: Client thread
Stacktrace:
	at bcw.az(SourceFile:1701)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bnm['__null'/2, l='MpServer', x=1192.09, y=12.32, z=1582.15]]
	Chunk stats: MultiplayerChunkCache: 1089, 1089
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (1205,9,1556), Chunk: (at 5,0,4 in 75,97; contains blocks 1200,0,1552 to 1215,255,1567), Region: (2,3; contains chunks 64,96 to 95,127, blocks 1024,0,1536 to 1535,255,2047)
	Level time: 330426 game time, 6000 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
	Forced entities: 3 total; [ze['Slime'/610, l='MpServer', x=1222.55, y=4.00, z=1569.15], bnm['__null'/2, l='MpServer', x=1223.39, y=4.00, z=1575.20], bnm['__null'/2, l='MpServer', x=1192.09, y=12.32, z=1582.15]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at blm.a(SourceFile:364)
	at bcw.b(SourceFile:2531)
	at bcw.a(SourceFile:401)
	at net.minecraft.client.main.Main.main(SourceFile:124)

-- System Details --
Details:
	Minecraft Version: 16w21a
	Operating System: Mac OS X (x86_64) version 10.11.5
	Java Version: 1.8.0_74, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 166470880 bytes (158 MB) / 506986496 bytes (483 MB) up to 932184064 bytes (889 MB)
	JVM Flags: 2 total; -Xms512M -Xmx1000M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 16w21a
	LWJGL: 2.9.2
	OpenGL: AMD Radeon R9 M290 OpenGL Engine GL version 2.1 ATI-1.42.11, ATI Technologies Inc.
	GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because ARB_framebuffer_object is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

	Using VBOs: Yes
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: Squares
	Current Language: English (Canada)
	Profiler Position: N/A (disabled)
	CPU: bcw$7@74f1c9b9