introduce direct loading for modules that need to be loaded in a given order becuase of missing dependencies, this fix the issue we had with early released of JDK7 and linux systems

Fixes #3509

spec/coverage_helper.rb

@@ -2,13 +2,33 @@
 # running coverage analysis
 module CoverageHelper
 
-  SKIP_LIST = ["lib/bootstrap/rspec.rb", "lib/logstash/util/prctl.rb"]
+  ##
+  # Skip list used to avoid loading certain patterns within
+  # the logstash directories, this patterns are excluded becuause
+  # of potential problems or because they are going to be loaded
+  # in another way.
+  ##
+  SKIP_LIST = Regexp.union([
+    /^lib\/bootstrap\/rspec.rb$/,
+    /^lib\/logstash\/util\/prctl.rb$/,
+    /^lib\/pluginmanager/
+  ])
+
+  ##
+  # List of files going to be loaded directly, this files
+  # are already loading their dependencies in the necessary
+  # order so everything is setup properly.
+  ##
+  DIRECT_LOADING_MODULES = [ "lib/pluginmanager/main.rb" ]
 
   def self.eager_load
     Dir.glob("lib/**/*.rb") do |file|
-      next if SKIP_LIST.include?(file)
+      next if file =~ SKIP_LIST
       require file
     end
+    DIRECT_LOADING_MODULES.each do |_module|
+      require _module
+    end
   end
 
 end