如何在Doctrine 2中使用多个targetEntity？

Question

I have two table:

Event.orm.yml

manyToOne:
    last_author:
        targetEntity: User
        inversedBy: last_author_contact
        joinColumn:
            name: last_author_id
            referencedColumnName: id

User.orm.yml

oneToMany:
    last_author_contact:
        targetEntity: Event
        mappedBy: last_author

Now I want add new "Project" entity which connected with "User" entity. So I must write in User.orm.yml:

oneToMany:
        last_author_contact:
            targetEntity: Event
            mappedBy: last_author
        last_author_project_contact:
            targetEntity: Project
            mappedBy: last_author_project

And create Project.orm.yml:

manyToOne:
        last_author_project:
            targetEntity: User
            inversedBy: last_author_project_contact
            joinColumn:
                name: last_author_id
                referencedColumnName: id

How can I use many targetEntity and can not write similar code in User entity (setters and getters)?

Like this:

oneToMany:
    last_author_contact:
        targetEntity: Event
        targetEntity: Project
        mappedBy: last_author