Guava is a suite of core and expanded libraries that include

The Apache Commons IO library contains utility classes, stream implementations, file filters,

Apache Commons Lang, a package of Java utility classes for the classes that are in java.lang's hierarchy, or are ...

Java annotations to use in Mojos

Plexus Component Java Annotations, to describe plexus components properties in java sources with

A collection of various utility classes to ease working with strings, files, command lines and

A collection of utility classes to ease usage of the repository system.

Core classes of Apache Maven to manage the building process.