private void register(LocationAndKind key, JavaFileObject javaFileObject) {
        if (!ramFileSystem.containsKey(key)) {
            ramFileSystem.put(key, new HashMap<String, JavaFileObject>());
        }
        ramFileSystem.get(key).put(javaFileObject.getName(), javaFileObject);
    }
MemFileManager is a memory based implementation of the JavaFileManager
interface

@author tiwe
querydsl-codegen-utils/src/main/java/com/querydsl/codegen/utils/MemFileManager.java