title: What does `[ERROR] Nothing <: com.some.SomeType?` mean?
body: <p>I have a project with scala and java. For scala compilation scala-maven-plugin is used.</p>
  
  <p>So during the build there are some messages like that:</p>
  
  <pre><code>[INFO] --- scala-maven-plugin:3.1.6:testCompile (scala-test-compile) @ project_name ---
  ...    
  [ERROR] Nothing &lt;: com.some.SomeType?
  [INFO] true
  ...
  </code></pre>
  
  <p>What does it mean? The source of scala class is below:</p>
  
  <pre><code>package com.some
  
  package object model {
  
    type SomeType = List[String]
  
    object SomeType {
      def apply(msg: String): SomeType = List(msg)
    }
  
    type SecondType[I] = AnyRef {
      def id: I
      def version: Long
    }
  
    type AnotherSecondType = SecondType[Another] {
      def id: Another
      def version: Long
    }
  
  }
  </code></pre>
  
  <p><strong>P.S.</strong> Also, there are other such message pairs for other scala classes.</p>
  
  <p><strong>UPDATED</strong>
  Maven build completes <strong>successfull</strong>, but I have these messages in the log.</p>