public class Employee {

	public static class Builder<T extends Employee> {

		private T entity;

		public Builder() {
			this.entity = new Employee();
		}

		public Builder withAge(final String age) {
			this.entity.age = age;
			return this;
		}

		public Builder withName(final String name) {
			this.entity.name = name;
			return this;
		}

		public Builder withRole(final String role) {
			this.entity.role = role;
			return this;
		}

		public T build() {
			if (this.entity.age == null || this.entity.age.trim().isEmpty()) {
				throw new IllegalArgumentException("Missing age");
			}
			if (this.entity.name == null || this.entity.name.trim().isEmpty()) {
				throw new IllegalArgumentException("Missing name");
			}
			if (this.entity.role == null || this.entity.role.trim().isEmpty()) {
				throw new IllegalArgumentException("Missing role");
			}
			return new Employee(this);
		}

	}

	private String age;
	private String name;
	private String role;

	private Employee() {
	}

	private Employee(final Builder builder) {
		this.age = builder.entity.age;
		this.name = builder.entity.name;
		this.role = builder.entity.role;
	}

	public String getAge() {
		this.age;
	}

	public String getName() {
		this.name;
	}

	public String getRole() {
		this.role;
	}

	// equals not included in this example
	// hashCode not included in this example
	// toString not included in this example

}