code: protected final void validateAuthenticationStatements(final List<AuthnStatement> authnStatements,
                                                            final SAML2MessageContext context) {
  
          for (final AuthnStatement statement : authnStatements) {
              if (!isAuthnInstantValid(statement.getAuthnInstant())) {
                  throw new SAMLAuthnInstantException("Authentication issue instant is too old or in the future");
              }
              if (statement.getSessionNotOnOrAfter() != null && statement.getSessionNotOnOrAfter().isBeforeNow()) {
                  throw new SAMLAuthnSessionCriteriaException("Authentication session between IDP and subject has ended");
              }
              // TODO implement authnContext validation
          }
      }
docs: Validate the given authnStatements:
  - authnInstant
  - sessionNotOnOrAfter
  
  @param authnStatements the authn statements
  @param context         the context