Fix the baseUrl is configured with a trailing slash

Signed-off-by: lance <leehaut@gmail.com>

Author: leehaut

mcp-core/src/main/java/io/modelcontextprotocol/util/UriBuilder.java

@@ -60,7 +60,7 @@ private UriBuilder(Builder builder) {
 	 */
 	public static Builder from(String url) {
 		if (url == null || url.isBlank()) {
-			throw new IllegalArgumentException("URL must not be null or blank");
+			return new Builder();
 		}
 
 		URI uri;

mcp-core/src/test/java/io/modelcontextprotocol/util/UriBuilderTests.java

@@ -12,6 +12,7 @@
 import org.junit.jupiter.params.provider.MethodSource;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 /**
  * Unit test for {@link UriBuilder}
@@ -45,6 +46,21 @@ void testSupportMultipleValues() {
 		assertThat(url).isEqualTo(BASE_URL + "?tag=java&tag=spring&tag=2025&debug");
 	}
 
+	@Test
+	void testFromEmptyString() {
+		UriBuilder.Builder builder = UriBuilder.from("");
+		UriBuilder uri = builder.build();
+		assertEquals("", uri.buildString());
+	}
+
+	@Test
+	void testFromSingleSlash() {
+		UriBuilder.Builder builder = UriBuilder.from("/");
+		UriBuilder uri = builder.build();
+
+		assertEquals("", uri.buildString());
+	}
+
 	static Stream<Arguments> pathProvider() {
 		return Stream.of(Arguments.of(BASE_URL, "/v1/users", "https://example.com/v1/users"),
 				Arguments.of(BASE_URL + "/", "v1/users", "https://example.com/v1/users"),