The Apache Commons IO are the components of the Apache Commons which are derived from Java API and provides various utility classes for common operations for File IO covering wide range of use cases. It helps avoid writing boilerplate code

The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms, it was developed by the Legion of the Bouncy Castle. The package is organised so that it contains a light-weight API suitable for use in any environment (including the newly released J2ME) with the additional infrastructure to conform the algorithms to the JCE framework. The Bouncy Castle Crypto APIs for Java consist of the following: A lightweight cryptography API. A provider for the Java Cryptography Extension and the Java Cryptography Architecture. A clean room implementation of the JCE 1.2.1. A library for reading and writing encoded ASN.1 objects. Lightweight APIs for TLS (RFC 2246, RFC 4346) and DTLS (RFC 4347). Generators for Version 1 and Version 3 X.509 certificates, Version 2 CRLs, and PKCS12 files. Generators for Version 2 X.509 attribute certificates. Generators/Processors for S/MIME and CMS (PKCS7/RFC 3852). Generators/Processors for OCSP (RFC 2560). Generators/Processors for TSP (RFC 3161 & RFC 5544). Generators/Processors for CMP and CRMF (RFC 4210 & RFC 4211). Generators/Processors for OpenPGP (RFC 4880). Generators/Processors for Extended Access Control (EAC). Generators/Processors for Data Validation and Certification Server (DVCS) - RFC 3029. Generators/Processors for DNS-based Authentication of Named Entities (DANE). Signed jar versions suitable for JDK 1.4-1.8 and the Sun JCE. The lightweight API works with everything from the J2ME to the JDK 1.8 and we now provide certificate generation, PKCS/CMS/CRMF/CMP/EAC/DANE/DVCS/TSP/TLS/DTLS and OpenPGP support across the full range of JDKs.

Gson is a Java library that can be used to convert Java Objects into their JSON representation. It can also be used to convert a JSON string to an equivalent Java object. Gson can work with arbitrary Java objects including pre-existing objects that you do not have source-code of.