Lambda formatting

private Map<Integer,? extends Address> getAddressIndex(Optional<SubjectData> currentSubjectData) {
	return currentSubjectData
		.map(subjectData -> subjectData
			.getAddresses()
                        .stream()
                        .filter(address -> address.getEsoId() != null)
                        .collect(toMap(Address::getEsoId, t -> t))
		)
		.orElse(emptyMap())
	;
}

// HYPOTHETICAL SOLUTION WITH GUAVA Optional:
private Map<Integer,? extends Address> getAddressIndex(Optional<SubjectData> currentSubjectData) {
	return currentSubjectData
		.asSet()  // Guava Optional's method, in JDK8 must be simulated with map(...).get()
		.stream()
		.flatMap(sd -> sd.getAddresses().stream())
		.filter(address -> address.getEsoId() != null)
		.collect(toMap(Address::getEsoId, t -> t))
	;
		//.orElse(emptyMap()); // unnecessary here, asSet did the work
}