either 1.5

• move static methods optionalList, toValidList, toValidListAll to a utility class: Eithers
• add Eithers.toOptionalList, which returns a collector that accumulates into Optional<List<T>>

either 1.4

• refactoring: inline internal helper methods to improve readability
• add optionalList, a static utility method that converts from List<E> to Optional<List<E>>, by mapping an empty List to an empty Optional, which can make it easier to express certain filter operations

either 1.3

• remove OptionalLeft
• getLeft() now returns an Optional

either 1.2

• Rename accept to ifPresentOrElse. This is a more familiar name.
• Remove acceptRight(Consumer). It can be expressed as getRight().ifPresent(Consumer).
• Remove acceptLeft(Consumer). It can be expressed as getLeft().ifPresent(Consumer).
• Performance improvement: map, flatMap and filter return the same Either instance, if invoked on a Left. Same applies to their left-side mirror methods, if invoked on a Right.

either 1.1

• remove io.jbock.util.Optional, use java.util.Optional instead