How to inject a custom Java keystore during S2I build process (PKIX path building failed)

Issue

When using source strategy (S2I) to build your own Java/Jboss/Tomcat images, it may be necessary the use of a custom CA in order to access a different Maven repository or to just inject your company's CA.

The usual error that appears during the build process if the proper CA is not present is the following:

Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: 

unable to find valid certification path to requested target
at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:397)
at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:302)
at sun.security.validator.Validator.validate(Validator.java:262)
at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:324)
at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:229)
at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:124)
at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1621)

NOTE: For problems related with Jenkins oAuth and custom CAs, please check on this other solution if needed.