[HTTPCLIENT-1889] org.apache.http.client.utils.URLEncodedUtils.parse()

should return a new ArrayList when there are no query parameters.

RELEASE_NOTES.txt

@@ -11,6 +11,10 @@ Changelog:
 * [HTTPCLIENT-1886] Update HttpClient 4.5.x from HttpCore 4.4.7 to 4.4.8
   Contributed by Gary Gregory <ggregory at apache.org>
 
+* [HTTPCLIENT-1889] org.apache.http.client.utils.URLEncodedUtils.parse() 
+  should return a new ArrayList when there are no query parameters.
+  Contributed by Gary Gregory <ggregory at apache.org>
+
 
 Release 4.5.4
 -------------------

httpclient/src/main/java/org/apache/http/client/utils/URLEncodedUtils.java

@@ -37,7 +37,6 @@
 import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.BitSet;
-import java.util.Collections;
 import java.util.List;
 import java.util.Scanner;
 
@@ -100,7 +99,7 @@ public static List <NameValuePair> parse(final URI uri, final Charset charset) {
         if (query != null && !query.isEmpty()) {
             return parse(query, charset);
         }
-        return Collections.emptyList();
+        return createEmptyList();
     }
 
     /**
@@ -120,14 +119,14 @@ public static List <NameValuePair> parse(
         Args.notNull(entity, "HTTP entity");
         final ContentType contentType = ContentType.get(entity);
         if (contentType == null || !contentType.getMimeType().equalsIgnoreCase(CONTENT_TYPE)) {
-            return Collections.emptyList();
+            return createEmptyList();
         }
         final long len = entity.getContentLength();
         Args.check(len <= Integer.MAX_VALUE, "HTTP entity is too large");
         final Charset charset = contentType.getCharset() != null ? contentType.getCharset() : HTTP.DEF_CONTENT_CHARSET;
         final InputStream instream = entity.getContent();
         if (instream == null) {
-            return Collections.emptyList();
+            return createEmptyList();
         }
         final CharArrayBuffer buf;
         try {
@@ -143,7 +142,7 @@ public static List <NameValuePair> parse(
             instream.close();
         }
         if (buf.length() == 0) {
-            return Collections.emptyList();
+            return createEmptyList();
         }
         return parse(buf, charset, QP_SEP_A);
     }
@@ -243,7 +242,7 @@ public static void parse(
      */
     public static List<NameValuePair> parse(final String s, final Charset charset) {
         if (s == null) {
-            return Collections.emptyList();
+            return createEmptyList();
         }
         final CharArrayBuffer buffer = new CharArrayBuffer(s.length());
         buffer.append(s);
@@ -266,7 +265,7 @@ public static List<NameValuePair> parse(final String s, final Charset charset) {
      */
     public static List<NameValuePair> parse(final String s, final Charset charset, final char... separators) {
         if (s == null) {
-            return Collections.emptyList();
+            return createEmptyList();
         }
         final CharArrayBuffer buffer = new CharArrayBuffer(s.length());
         buffer.append(s);
@@ -520,6 +519,10 @@ public static String format(
 
     private static final int RADIX = 16;
 
+    private static List<NameValuePair> createEmptyList() {
+        return new ArrayList<NameValuePair>(0);
+    }
+
     private static String urlEncode(
             final String content,
             final Charset charset,

httpclient/src/test/java/org/apache/http/client/utils/TestURLEncodedUtils.java

@@ -169,6 +169,14 @@ public void testParseInvalidURLCodedContent() throws Exception {
         assertNameValuePair(result.get(0), "name", "%wa ");
     }
 
+    @Test
+    public void testEmptyQuery() throws Exception {
+        final List<NameValuePair> result = URLEncodedUtils.parse("", Consts.UTF_8);
+        Assert.assertEquals(0, result.size());
+        // [HTTPCLIENT-1889]:
+        result.add(new BasicNameValuePair("key", "value"));
+    }
+
     @Test
     public void testParseEntity() throws Exception {
         final StringEntity entity = new StringEntity("Name1=Value1");