import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.Column;
import javax.persistence.ElementCollection;
import javax.persistence.Entity;
import javax.persistence.Id;
import org.hibernate.envers.Audited;

@Entity
@Audited
public class TestEntity implements Serializable {

    @Id
    private Long id;

    @ElementCollection
    @Column(length = 1024)
    private List<String> strings = new ArrayList<>();

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public List<String> getStrings() {
        return strings;
    }

    public void setStrings(List<String> strings) {
        this.strings = strings;
    }
}

create table TestEntity (id bigint not null, primary key (id))
create table TestEntity_AUD (id bigint not null, revision integer not null, action tinyint, primary key (id, revision))
create table TestEntity_strings (TestEntity_id bigint not null, strings longtext)
reate table TestEntity_strings_AUD (revision integer not null, TestEntity_id bigint not null, strings longtext not null, action tinyint, primary key (revision, TestEntity_id, strings))

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: BLOB/TEXT column 'strings' used in key specification without a key length