fix: Ensure protocol slashes are preserved in getSanitizedPath

spring-web/src/main/java/org/springframework/web/util/UriComponentsBuilder.java

@@ -908,16 +908,20 @@ public PathComponent build() {
 		}
 
 		private static String getSanitizedPath(final StringBuilder path) {
-			int index = path.indexOf("//");
-			if (index >= 0) {
-				StringBuilder sanitized = new StringBuilder(path);
-				while (index != -1) {
-					sanitized.deleteCharAt(index);
-					index = sanitized.indexOf("//", index);
-				}
-				return sanitized.toString();
+			String pathString = path.toString();
+			int protocolIndex = pathString.indexOf("://");
+			boolean hasProtocol = protocolIndex != -1;
+
+			if (hasProtocol) {
+				String protocol = path.substring(0, protocolIndex + 3);
+				String restOfPath = path.substring(protocolIndex + 3);
+
+				String sanitizedRestPath = restOfPath.replaceAll("/{2,}", "/");
+
+				return protocol + sanitizedRestPath;
 			}
-			return path.toString();
+
+			return pathString.replaceAll("/{2,}", "/");
 		}
 
 		public void removeTrailingSlash() {

spring-web/src/test/java/org/springframework/web/util/UriComponentsBuilderTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.web.util;
 
+import java.lang.reflect.Method;
 import java.net.URI;
 import java.util.Arrays;
 import java.util.Collection;
@@ -25,10 +26,13 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.function.BiConsumer;
+import java.util.stream.Stream;
 
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.EnumSource;
+import org.junit.jupiter.params.provider.MethodSource;
 
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
@@ -890,4 +894,37 @@ void expandPortAndPathWithoutSeparator(ParserType parserType) {
 		assertThat(uri.toString()).isEqualTo("ws://localhost:7777/test");
 	}
 
+	@ParameterizedTest
+	@MethodSource("providePathsForSanitization")
+	void verifySanitizedPath(StringBuilder inputPath, String expected) {
+		assertThat(invokeGetSanitizedPath(inputPath)).isEqualTo(expected);
+	}
+
+	private static Stream<Arguments> providePathsForSanitization() {
+		return Stream.of(
+				Arguments.of(new StringBuilder("https://example.com//path/to//resource"), "https://example.com/path/to/resource"),
+				Arguments.of(new StringBuilder("https://example.com//path"), "https://example.com/path"),
+				Arguments.of(new StringBuilder("example.com//path"), "example.com/path"),
+				Arguments.of(new StringBuilder("example.com//////////////path//to"), "example.com/path/to")
+		);
+	}
+
+	private String invokeGetSanitizedPath(StringBuilder path) {
+		try {
+			Class<?> outerClass = Class.forName("org.springframework.web.util.UriComponentsBuilder");
+
+			Class<?> innerClass = Arrays.stream(outerClass.getDeclaredClasses())
+					.filter(clazz -> clazz.getSimpleName().equals("FullPathComponentBuilder"))
+					.findFirst()
+					.orElseThrow(() -> new ClassNotFoundException("FullPathComponentBuilder not found"));
+
+			Method method = innerClass.getDeclaredMethod("getSanitizedPath", StringBuilder.class);
+			method.setAccessible(true);
+			return (String) method.invoke(null, path);
+		}
+		catch (Exception e) {
+			throw new RuntimeException("Failed to invoke getSanitizedPath", e);
+		}
+	}
+
 }