Person.java

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

public class Person {

    private String name;

    private String lastName;

    private List<String> expertises = new ArrayList<>();

    public Person() {}

    public Person(String name, String lastName) {
        this.name = name;
        this.lastName = lastName;
    }

    public String getFullName() {
        return name + ' ' + lastName;
    }

    public List<String> getExpertises() {
        return expertises;
    }

    public void add(String e) {
        expertises.add(e);
    }

    public void removeJTech() {
        expertises = expertises.stream().filter(i -> i.charAt(0) != 'j').collect(Collectors.toList());
    }

    public String getCommaSeparated() {
        return expertises.stream().collect(Collectors.joining(", "));
    }

    @Override
    public boolean equals(Object o) {
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;

        Person person = (Person) o;

        if (name != null ? !name.equals(person.name) : person.name != null)
            return false;
        return lastName != null ? lastName.equals(person.lastName) : person.lastName == null;

    }

    @Override
    public int hashCode() {
        int result = name != null ? name.hashCode() : 0;
        result = 31 * result + (lastName != null ? lastName.hashCode() : 0);
        return result;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
}