Jar's can be found here: https://bintray.com/robstoll/tutteli-jars/atrium/0.3.0
API Maturity: Almost Stable
Implementation Maturity: Development
(I provide a more or less a stable API for users of Atrium but not yet for implementers of atrium)

Included in this release:

assertion functions

• lazily and immediately evaluated assertions
• assertion for nullable types
• assertions about thrown exceptions
• feature assertions for properties and return values of methods
• and a minimal set of assertion functions

Components

• Translator including a PropertiesBasedTranslationSupplier
• OnlyFailureReporting
• SameLineAssertionFormatter
• DetailedObjectFormatter
• ArgumentFormatter

Improvements compared to 0.2.0

• i18n support for assertions and assertion verbs
• feature assertion for methods (0.2.0 had only feature assertions for properties)
• a few more assertion functions
• improved formatting in DetailObjectFormatter (boolean, enums, and KClass are treated specially)
• further improved Code-Documentation incl. a better readable layout (see KDoc)

Not included in this release yet

• basic assertion functions for collections (containsOnly, contains, containsNot, containsInOrder etc.)