Why do the source folders in package explorer appear in not alphabetical order

I'm looking at a few projects in Eclipse's Package Explorer.

I expect to see the items listed in this order:

My Awesome Project 
+ src/main/java
+ src/test/java
+ src/test/resources

The first project in my list meets this expectation, but the second project appears in this order

My Less Awesome Project 
+ src/test/java
+ src/test/resources
+ src/main/java

Is there a setting I can change to get the source folders to appear in the way I expect them to? I'm using Luna-Eclipse