code cleanups and integration work for defaulting to Java Event implementation

cleaned dependencies, removed Guava code

default to java event

also compile java event

use json-unit for json result assertions

remove Java 8 specific constructs to be able to compile on Java 7

use jar-dependencies

better jar file loading

copy jar into lib after build

add post-build copy and clean of gem jar and re-indented file

fix jar destination

include generated jar in gem

remove useless ArrayList constructions

add tests for KeyNode.join method

remove useless  shadow and disable unchecked warnings

update gradle dependency to 2.8

fix deprecated asserEquals usage

simplify convoluted list contruction

fix array fields nil values handling

moar nil value tests

simplify for loop

logstash-core-event-java/lib/logstash-core-event-java/logstash-core-event-java.rb

@@ -5,14 +5,7 @@ require "java"
 module LogStash
 end
 
-# TODO: (colin) integrate jar loading with gradle and verify dev vs prod environment setups
-
-# insert all jars in this directory into CLASSPATH
-Dir.glob(File.join(File.expand_path("..", __FILE__), "*.jar")).each do |jar|
-  $CLASSPATH << jar unless $CLASSPATH.include?(jar)
-end
-
-# TODO: (colin) correctly handle dev env build/ dir and local jar
+require "logstash-core-event-java_jars"
 
 # local dev setup
 classes_dir = File.expand_path("../../../build/classes/main", __FILE__)
@@ -22,7 +15,13 @@ if File.directory?(classes_dir)
   $CLASSPATH << classes_dir unless $CLASSPATH.include?(classes_dir)
 else
   # otherwise use included jar
-  raise("TODO build dir not found and no jar file")
+  begin
+    jar = Dir[File.dirname(__FILE__) + "/logstash-core-event-java*.jar"].first
+    raise("No logstash-core-event-java jar file found") unless jar
+    require jar
+  rescue Exception => e
+    raise("Error loading logstash-core-event-java jar file, cause: #{e.message}")
+  end
 end
 
 require "jruby_event_ext"

logstash-core-event-java/lib/logstash-core-event-java_jars.rb

@@ -0,0 +1,5 @@
+# this is a generated file, to avoid over-writing it just delete this comment
+require 'jar_dependencies'
+
+require_jar( 'org.codehaus.jackson', 'jackson-core-asl', '1.9.13' )
+require_jar( 'org.codehaus.jackson', 'jackson-mapper-asl', '1.9.13' )