Version 2.8.4

• [java-security] Make HybridTokenFactory more failure tolerant
• [spring-xsuaa-test] Prefills "ext_atr" "enhancer" with XSUAA

Update Versions

• [all]
  • commons-io 2.6 --> 2.8.0
  • org.apache.httpcomponents » httpclient 4.5.9 --> 4.5.13
  • spring.core.version 5.3.2 --> 5.3.3
  • spring.boot.version 2.4.1 --> 2.4.2
• [java-security-test]
  • org.eclipse.jetty 9.4.35.v20201120 --> 9.4.36.v20210114
• [token-client]
  • caffeine 2.8.6 --> 2.8.8
  • org.json 20200518 --> 20201115
• [spring-xsuaa]
  • caffeine 2.8.6 --> 2.8.8
  • reactor-core 3.3.7.RELEASE --> 3.4.2
  • log4j-to-slf4j 2.13.3 --> 2.14.0