ParsePerson.java

    /**
     * Parse the lines to extract relevant attributes.
     * <ul>
     *     <li>Each line contains only 1 value as key:value</li>
     *     <li>We are only interested in the attributes that are present in the Attribute enum.</li>
     *     <li>Name and Country must be present otherwise we'll throw PersonNotFoundException.</li>
     *     <li>These lines may not have all the attributes. For the missing attributes we'll set the value to NULL</li>
     *     <li>These lines may contain extra attributes that we are not interested in. Those should be ignored.</li>
     * </ul>
     *
     * @param lines The key:value pair of attribute values that needs to be parsed.
     *
     * @return The Person object parsed from the lines.
     */
    public static Person parsePerson(final List<String> lines) {
        // We'll read all the lines and collect the attributes in a map.
        final Map<Attribute, List<String>> values =
                lines.parallelStream()
                     .map(l -> l.split(":"))
                     .filter(a -> a.length == 2)
                     .filter(a -> Attribute.from(a[0].trim()).isPresent())
                     .collect(Collectors.groupingBy(a -> Attribute.from(a[0].trim()).get(),
                                                    Collectors.mapping(a -> a[1].trim(), Collectors.toList())));

        return new Person(getValue(values, Attribute.NAME).orElseThrow(PersonNotFoundException::new),
                          parseCountry(values).orElseThrow(PersonNotFoundException::new),
                          getValue(values, Attribute.EMAIL_ADDRESS).orElse(null));
    }