Guava is a set of core libraries that includes new collection types (such as multimap and multiset), immutable collections, a graph library, and utilities for concurrency, I/O, hashing, primitives, strings, and more!
Truth is a library for performing assertions in tests. Truth makes your test assertions and failure messages more readable. Similar to AssertJ, it natively supports many JDK and Guava types, and it is extensible to others. Truth is owned and maintained by the Guava team. It is used in the majority of the tests in Google’s own codebase.
General purpose utilities and hash functions for Android and Java
...The library is compatible with both Android and standard Java environments, making it broadly usable across platforms. Overall, Essentials serves developers who want faster and more convenient core utilities without adopting large libraries like Guava or Apache Commons.