tracing an sbt eviction regarding plugins.sbt - sbt

Question

I seem to be unable finding the root cause of the first eviction seen below. As seen below, running evicted does not provide details relevant to it.
This all occurs after having added in project/plugins.sbt:
libraryDependencies += "io.spray" %% "spray-json" % "1.3.1"
[warn] There may be incompatibilities among your library dependencies.
[warn] Here are some of the libraries that were evicted:
[warn] * io.spray:spray-json_2.10:1.2.6 -> 1.3.1
[warn] Run 'evicted' to see detailed eviction warnings
[projectName] $ evicted
[info] Resolving jline#jline;2.12.1 ...
[info] Done updating.
[warn] There may be incompatibilities among your library dependencies.
[warn] Here are some of the libraries that were evicted:
[warn] * com.googlecode.efficient-java-matrix-library:ejml:0.23 -> 0.19 (caller: edu.arizona.sista:processors:3.3, edu.stanford.nlp:stanford-corenlp:3.3.1)
[warn] * com.google.guava:guava:(15.0, 13.0.1) -> 16.0.1 (caller: org.sorm-framework:sorm:0.3.16, com.jolbox:bonecp:0.8.0.RELEASE, com.typesafe.play:play-ws_2.11:2.3.7)
[warn] * xml-apis:xml-apis:(2.0.2, 1.3.03) -> 1.4.01 (caller: xalan:xalan:2.7.0, xerces:xercesImpl:2.11.0, xom:xom:1.2.5, com.io7m.xom:xom:1.2.10)
[warn] * io.netty:netty:(3.9.2.Final, 3.6.3.Final) -> 3.9.3.Final (caller: com.ning:async-http-client:1.8.14, com.typesafe.netty:netty-http-pipelining:1.1.2, com.typesafe.play:play_2.11:2.3.7)
[success] Total time: 2 s, completed Apr 9, 2015 8:04:11 PM
At runtime, I get this crash without even trying to use spray-json, so something really isn't right about how this dependency is managed or evicted in my sbt build:
[error] (web-assets:less::jstaskJsOptions) java.lang.NoSuchMethodError: spray.json.JsArray.<init>(Lscala/collection/immutable/List;)V
There is no version 1.2.6 of this dependency explicitly defined in my build.sbt in the first place, maybe it is required by other plugins there, but how can that be traced without the eviction details? How can I fathom the details of this mysterious eviction?

Answer 1

You can use
show externalDependencyClasspath
to get the toString representation that includes all transitive dependencies but it looks quite cumbersome. I suggest to install the sbt-dependency-graph plugin which makes the dependencyTree task available, that shows you your full classpath in a readable format.