Use consistent ternary expression style

Update all ternary expressions so that the condition is always in
parentheses and "not equals" is used in the test. This helps to bring
consistency across the codebase which makes ternary expression easier
to scan.

For example: `a = (a != null) ? a : b`

Issue gh-8945

rsocket/src/main/java/org/springframework/security/rsocket/util/matcher/PayloadExchangeMatcher.java

@@ -81,7 +81,9 @@ public interface PayloadExchangeMatcher {
 		 * @return
 		 */
 		public static Mono<MatchResult> match(Map<String, ? extends Object> variables) {
-			return Mono.just(new MatchResult(true, variables == null ? null : new HashMap<String, Object>(variables)));
+			MatchResult result = new MatchResult(true,
+					(variables != null) ? new HashMap<String, Object>(variables) : null);
+			return Mono.just(result);
 		}
 
 		/**