https://javadoc.io/doc/org.bouncycastle/bcprov-lts8on/latest/index.html shows no X509CRLParser and in the jars of 2.73.0 or 2.73.7 the class is also missing.
org/bouncycastle/jce/provider/X509CRLParser is available in 1.73 or 1.79, the former is stated to be the base of 2.73, the later is stated to be the base of 2.73.7.
Issue seems to be with LTS build only. X509CRLParser class is present in bcgit repo, but missing in bc-lts-java.
Initially reported here: bcgit/bc-java#2132