Can we replace Guava with Java 8 features? If we keep it should be upgraded to a more recent version

[TheSnoozer]

Just a thought....we use guava for some common utility stuff.
With Java 8 some of Guava's stuff can be replaced with native Java code.
If there would no additional benefit in using guava it should be a replaced with native Java code.
This is just an evaluation if we can replace all current features with native code.
If not we keep guava (but should upgrade it to a more recent version).

Only thing that we seem to use (and might be useful) is an immutable map where no such replacement seem to exist inside the native java 8 environment.

https://www.reddit.com/r/java/comments/217rnf/what_is_obsolete_in_guava_since_java_8/

FluentIterable
Stream

{Listenable,Settable}Future
CompletableFuture

Sets.newConcurrentHashSet()
ConcurrentHashMap.newKeySet()

Joiner.on(separator).join(...)
String.join(separator, ...)
...or new StringJoiner(separator).add(...)
...or stream.collect(Collectors.joining(separator))

com.google.common.base.{Predicate,Function,Supplier,Optional}
java.util.function.{Predicate,Function,Supplier}, java.util.Optional (and Optional{Int,Long,Double})

Ordering.natural()
Comparator.naturalOrder()

ordering.reverse()
comparator.reversed()

Ordering.compound(comparator1, comparator2)
comparator1.thenComparing(comparator2)

Ordering.from(comparator).onResultOf(function)
Comparator.comparing(function, comparator)

Ordering.from(comparator).nulls{First,Last}()
Comparator.nulls{First,Last}(comparator)

ComparisonChain
comparator.thenComparing(...)

Some uses of BaseEncoding
java.util.Base64

Lists.transform(list, function)
list.stream().map(function).collect(Collectors.toList())

• More verbose, less efficient.

Maps.uniqueIndex(collection, function)
collection.stream().collect(Collectors.toMap(Function.identity(), function))

• More verbose, not immutable.

Multimaps.index(collection, function)
collection.stream().collect(Collectors.groupingBy(function))

• More verbose, not immutable, not a Multimap.

https://groups.google.com/forum/#!topic/guava-discuss/fEdrMyNa8tA

com.google.common.base.Function -> java.util.function.Function

com.google.common.base.Supplier -> java.util.function.Supplier

void com.google.common.util.concurrent.ListenableFuture addListener(Runnable listener, Executor executor) method -> CompletableFuture java.util.concurrent.CompletableFuture.thenRunAsync(Runnable action, Executor executor) (.... instead of returning a void, this returns a CompletableFuture ).

com.google.common.util.concurrent.ListenableFuture.addListener(someRunnable, MoreExecutors.sameThreadExecutor() ) -> java.util.concurrent.CompletableFuture.thenRun( someRunnable )

com.google.common.util.concurrent.Futures.addCallback(..) -> doesn't exist

com.google.common.util.concurrent.SettableFuture.set(T) -> java.util.concurrent.CompletableFuture.complete(T)

boolean com.google.common.base.Predicate.apply(T) -> boolean java.util.function.Predicate.test(T)

com.google.common.base.Predicates.and/or/not -> java.util.function.Predicate.and/or/negate

com.google.common.base.Optional -> java.util.Optional

com.google.common.base.Joiner -> java.util.StringJoiner (roughly)

[TheSnoozer]

I removed almost every (unnecessary) call that could be replaced with java8.
There is only a few items left where we ask guava for certain thinks.
Not sure if it would be worth to replace this with our own custom logic.
All together I updated it to the latest version available and thus i feel I just can close the ticket for now and if there is a need to full remove the dependency i think we just can go ahead and do it.