Reproduce exception with PriorityQueue with lambda expression

[Jiayi-Liao]

The pull request is to reproduce the exception described in #421

Set the java version to 1.8 because the problem is about java 1.8 lambda expression.

[CLAassistant]

All committers have signed the CLA.

[nevillelyh]

Some builds failed because of sbt classloading:

[error] Test suite com.twitter.chill.java.PriorityQueueSpec failed with java.lang.ClassNotFoundException: com.twitter.chill.java.TestPriorityQueue$$Lambda$6275/1415420090.
[error] This may be due to the ClassLoaderLayeringStrategy (ScalaLibrary) used by your task.
[error] To improve performance and reduce memory, sbt attempts to cache the class loaders used to load the project dependencies.
[error] The project class files are loaded in a separate class loader that is created for each test run.
[error] The test class loader accesses the project dependency classes using the cached project dependency classloader.
[error] With this approach, class loading may fail under the following conditions:
[error] 
[error]  * Dependencies use reflection to access classes in your project's classpath.
[error]    Java serialization/deserialization may cause this.
[error]  * An open package is accessed across layers. If the project's classes access or extend
[error]    jvm package private classes defined in a project dependency, it may cause an IllegalAccessError
[error]    because the jvm enforces package private at the classloader level.
[error] 
[error] These issues, along with others that were not enumerated above, may be resolved by changing the class loader layering strategy.
[error] The Flat and ScalaLibrary strategies bundle the full project classpath in the same class loader.
[error] To use one of these strategies, set the  ClassLoaderLayeringStrategy key
[error] in your configuration, for example:
[error] 
[error] set chill-java / Test / classLoaderLayeringStrategy := ClassLoaderLayeringStrategy.ScalaLibrary
[error] set chill-java / Test / classLoaderLayeringStrategy := ClassLoaderLayeringStrategy.Flat
[error] 
[error] See ClassLoaderLayeringStrategy.scala for the full list of options.

Try adding the suggested settings above?