Handy URI Templates is a RFC6570 compliant URI template processor. The library allows clients to

Linear time regular expressions for Java

Apache Commons Validator provides the building blocks for both client-side and server-side data validation.

JSON is a light-weight, language independent, data interchange format.

Guava is a suite of core and expanded libraries that include

EqualsVerifier can be used in JUnit unit tests to verify whether the contract for the equals and hashCode methods is ...

Core API and libraries of hamcrest matcher framework.

Module "junit-jupiter" of JUnit

Mockito mock objects library core API and implementation