[MC-105204] sounds.json default namespace always gets added, even if one is provided

When you add sound events to the sounds.json using a resource pack and add a namespace, the default namespace (minecraft: ) gets added in front of the event.

Download the resource pack provided, activate it, and see the following message:

File minecraft:sounds/lm/burning_blaze.ogg does not exist, cannot add it to event minecraft:lm:burning_blaze

The sounds.json provided states:

{
  "lm:burning_blaze": {
  "category": "ambient",
    "sounds": [
	  {
        "name": "lm/burning_blaze",
        "stream": true
      }
    ],
    "subtitle": "burning blaze's battle music"
  }
}

Note, no "minecraft:"

Moving the sounds.json from the minecraft folder to the lm folder does nothing but state a unrelated pack.mcmeta error:

[22:35:52] [Client thread/WARN]: Unable to parse metadata section of resourcepack: bug test.zip
bye: 'pack.mcmeta' in ResourcePack 'xxxxxxxxxxx\.minecraft\resourcepacks\bug test.zip'
	at bxu.a(SourceFile:40) ~[16w32b.jar:?]
	at bxo.a(SourceFile:60) ~[16w32b.jar:?]
	at byl.a(SourceFile:43) [16w32b.jar:?]
	at bdo.f(SourceFile:737) [16w32b.jar:?]
	at bih.a(SourceFile:133) [16w32b.jar:?]
	at bgk.a(SourceFile:340) [16w32b.jar:?]
	at bih.a(SourceFile:141) [16w32b.jar:?]
	at bgk.k(SourceFile:403) [16w32b.jar:?]
	at bih.k(SourceFile:77) [16w32b.jar:?]
	at bgk.p(SourceFile:380) [16w32b.jar:?]
	at bdo.t(SourceFile:1583) [16w32b.jar:?]
	at bdo.av(SourceFile:967) [16w32b.jar:?]
	at bdo.a(SourceFile:395) [16w32b.jar:?]
	at net.minecraft.client.main.Main.main(SourceFile:124) [16w32b.jar:?]