play-ws and play-ws-standalone conflict on play.api.libs.ws{package$, package}

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A project depending on "com.typesafe.play" %% "play-ws" % "2.6.3" brings in transitively

[info]   +-com.typesafe.play:play-ws_2.12:2.6.3 [S]
[info]   | +-com.typesafe.play:play-ws-standalone-json_2.12:1.0.4 [S]
...
[info]   | | +-com.typesafe.play:play-ws-standalone_2.12:1.0.4 [S]

which causes sbt-assembly to fail because play-ws and play-ws-standalone both define the aformentioned classes, with different contents in at least one case for the versions mentioned.

Play WS Version (2.5.x / etc)

2.6.3 / 1.0.4 (standalone)

Expected Behavior

Expected to be able to package my code using play-ws using sbt-assembly.

Actual Behavior

[error] 2 errors were encountered during merge
java.lang.RuntimeException: deduplicate: different file contents found in the following:
/root/.ivy2/cache/com.typesafe.play/play-ws_2.12/jars/play-ws_2.12-2.6.3.jar:play/api/libs/ws/package$.class
/root/.ivy2/cache/com.typesafe.play/play-ws-standalone_2.12/jars/play-ws-standalone_2.12-1.0.4.jar:play/api/libs/ws/package$.class
deduplicate: different file contents found in the following:
/root/.ivy2/cache/com.typesafe.play/play-ws_2.12/jars/play-ws_2.12-2.6.3.jar:play/api/libs/ws/package.class
/root/.ivy2/cache/com.typesafe.play/play-ws-standalone_2.12/jars/play-ws-standalone_2.12-1.0.4.jar:play/api/libs/ws/package.class

Start by reproducing the dependency graph for play-ws 2.6.3 and play-ws-standalone 1.0.4, then run sbt-assembly against the reported duplicate play/api/libs/ws/package classes. Inspect how these artifacts are published and packaged; done means the dependency combination can be assembled without conflicting class contents.