Allow Info to be built with null map values

Fixes gh-48401

Author: philwebb

module/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/info/Info.java

@@ -116,7 +116,7 @@ public Builder withDetail(String key, @Nullable Object value) {
 		 * @return this {@link Builder} instance
 		 * @see #withDetail(String, Object)
 		 */
-		public Builder withDetails(Map<String, Object> details) {
+		public Builder withDetails(Map<String, @Nullable ? extends Object> details) {
 			this.content.putAll(details);
 			return this;
 		}