Update Spring Security build to require JDK 11

[jzheaux]

The latest OpenSAML major version (4.x) requires JDK 11, and the earlier OpenSAML version (3.x) has reached its end of life. In order to complete #9095, it is required to build with JDK 11.

To update to JDK 11 will require the following:

• Migrate LDAP samples to use UnboundIdContainer - Migrate LDAP samples to use UnboundIdContainer #9414
• Remove javax.annotation usage - Remove javax.annotation Usage from LDAP Tests #9415
• Rework LDAP ApacheDS tests to work with JDK 11 - Rework LDAP ApacheDS tests to work with JDK 11  #9416
• Update Git workflows to use JDK 11 - Update Git workflows to require JDK 11 #9417
• Update community guidelines to require JDK 11 - Update contribution guidelines to require JDK 11 to build #9418
• R2dbcReactiveOAuth2AuthorizedClientServiceTests should anticipate a lower-precision timestamp - R2dbcReactiveOAuth2AuthorizedClientServiceTests should anticipate a lower-precision timestamp #9449
• OAuth2AuthenticationTokenMixinTests should anticipate a lower-precision timestamp - OAuth2AuthenticationTokenMixinTests should anticipate a lower-precision timestamp #9461