Add a test for escaped chars in java_opts vars

This commit adds a test to prove that escaped chars are handled correctly in the environment variable values of `java_opts`.

Author: Christopher Frost

spec/java_buildpack/framework/java_opts_spec.rb

@@ -86,6 +86,18 @@
     end
   end
 
+  context do
+    let(:configuration) do
+      { 'java_opts' => '-javaagent:agent.jar=port="\$PORT",host=localhost' }
+    end
+
+    it 'allows escaped characters' do
+      component.release
+
+      expect(java_opts).to include('-javaagent:agent.jar=port=$PORT,host=localhost')
+    end
+  end
+
   context do
     let(:configuration) { { 'java_opts' => '-Xms1024M' } }