Normalize the http-root-path at config level

I think it's better to make sure it's always consistent. '/' is a bit of
a special case right now and not entirely consistent with the no slash
at the end rule but I think we can live with it.

Fixes #19492

extensions/vertx-http/runtime/src/main/java/io/quarkus/vertx/http/runtime/HttpBuildTimeConfig.java

@@ -2,9 +2,12 @@
 
 import java.time.Duration;
 
+import org.eclipse.microprofile.config.spi.Converter;
+
 import io.quarkus.runtime.annotations.ConfigItem;
 import io.quarkus.runtime.annotations.ConfigPhase;
 import io.quarkus.runtime.annotations.ConfigRoot;
+import io.quarkus.runtime.annotations.ConvertWith;
 import io.vertx.core.http.ClientAuth;
 
 @ConfigRoot(name = "http", phase = ConfigPhase.BUILD_AND_RUN_TIME_FIXED)
@@ -14,6 +17,7 @@ public class HttpBuildTimeConfig {
      * The HTTP root path. All web content will be served relative to this root path.
      */
     @ConfigItem(defaultValue = "/")
+    @ConvertWith(NormalizeHttpRootPathConverter.class)
     public String rootPath;
 
     public AuthConfig auth;
@@ -43,7 +47,7 @@ public class HttpBuildTimeConfig {
      * Non-application endpoints will be served from the specified path.
      * * `${quarkus.http.root-path}` -> Setting this path to the same value as HTTP root path disables
      * this root path. All extension-provided endpoints will be served from `${quarkus.http.root-path}`.
-     * 
+     *
      * @asciidoclet
      */
     @ConfigItem(defaultValue = "q")
@@ -54,4 +58,29 @@ public class HttpBuildTimeConfig {
      */
     @ConfigItem(defaultValue = "30s")
     public Duration testTimeout;
+
+    public static class NormalizeHttpRootPathConverter implements Converter<String> {
+
+        private static final String SLASH = "/";
+
+        @Override
+        public String convert(String value) throws IllegalArgumentException, NullPointerException {
+            if (value == null) {
+                return SLASH;
+            }
+
+            value = value.trim();
+            if (SLASH.equals(value)) {
+                return value;
+            }
+            if (!value.startsWith(SLASH)) {
+                value = SLASH + value;
+            }
+            if (value.endsWith(SLASH)) {
+                value = value.substring(0, value.length() - 1);
+            }
+
+            return value;
+        }
+    }
 }