Is it possible to have OneToMany relation, but have collection of primitive's instead of collection of entities?

Hibernate doesn't play nice with primitives, but you can certainly use built-in classes that wrap primitives (e.g. Integer, Character, etc.) or any other scalar type that has an analog in your database:

http://www.hibernate.org/hib_docs/v3/re ... s-ofvalues

Example using annotations (you need to change some names to fit your need)

@CollectionOfElements
@JoinTable(name = "somename_othername",
joinColumns = @JoinColumn(name = "some_id"))
@Column(name = "some_column", length = MAX_SOME_LENGTH)
@Immutable
private Set<String> someCollection;