UriComponentBuilder allows for multiple independent build() calls on same builder instance

Issue: SPR-11885
(cherry picked from commit c73ac07)

Author: jhoeller

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

@@ -649,7 +649,7 @@ static final class PathSegmentComponent implements PathComponent {
 		private final List<String> pathSegments;
 
 		public PathSegmentComponent(List<String> pathSegments) {
-			this.pathSegments = Collections.unmodifiableList(pathSegments);
+			this.pathSegments = Collections.unmodifiableList(new ArrayList<String>(pathSegments));
 		}
 
 		public String getPath() {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,7 @@
 import java.util.Map;
 
 import org.junit.Test;
+
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 
@@ -50,6 +51,28 @@ public void plain() throws URISyntaxException {
 		assertEquals("Invalid result URI", expected, result.toUri());
 	}
 
+	@Test
+	public void multipleFromSameBuilder() throws URISyntaxException {
+		UriComponentsBuilder builder = UriComponentsBuilder.newInstance().scheme("http").host("example.com").pathSegment("foo");
+		UriComponents result1 = builder.build();
+		builder = builder.pathSegment("foo2").queryParam("bar").fragment("baz");
+		UriComponents result2 = builder.build();
+
+		assertEquals("http", result1.getScheme());
+		assertEquals("example.com", result1.getHost());
+		assertEquals("/foo", result1.getPath());
+		URI expected = new URI("http://example.com/foo");
+		assertEquals("Invalid result URI", expected, result1.toUri());
+
+		assertEquals("http", result2.getScheme());
+		assertEquals("example.com", result2.getHost());
+		assertEquals("/foo/foo2", result2.getPath());
+		assertEquals("bar", result2.getQuery());
+		assertEquals("baz", result2.getFragment());
+		expected = new URI("http://example.com/foo/foo2?bar#baz");
+		assertEquals("Invalid result URI", expected, result2.toUri());
+	}
+
 	@Test
 	public void fromPath() throws URISyntaxException {
 		UriComponents result = UriComponentsBuilder.fromPath("foo").queryParam("bar").fragment("baz").build();