NimbusReactiveJwtDecoder support mono chain

Supports reactive exception handling when using PublicKeyReactiveJwtDecoderBuilder and SecretKeyReactiveJwtDecoderBuilder

oauth2/oauth2-jose/src/main/java/org/springframework/security/oauth2/jwt/NimbusReactiveJwtDecoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -488,7 +488,7 @@ public final class NimbusReactiveJwtDecoder implements ReactiveJwtDecoder {
 			jwtProcessor.setJWTClaimsSetVerifier((claims, context) -> {
 			});
 			this.jwtProcessorCustomizer.accept(jwtProcessor);
-			return (jwt) -> Mono.just(createClaimsSet(jwtProcessor, jwt, null));
+			return (jwt) -> Mono.fromCallable(() -> createClaimsSet(jwtProcessor, jwt, null));
 		}
 
 	}
@@ -563,7 +563,7 @@ public final class NimbusReactiveJwtDecoder implements ReactiveJwtDecoder {
 			jwtProcessor.setJWTClaimsSetVerifier((claims, context) -> {
 			});
 			this.jwtProcessorCustomizer.accept(jwtProcessor);
-			return (jwt) -> Mono.just(createClaimsSet(jwtProcessor, jwt, null));
+			return (jwt) -> Mono.fromCallable(() -> createClaimsSet(jwtProcessor, jwt, null));
 		}
 
 	}