HTTPCORE-770: Introduced plusAsBlank parameter for dynamic configuration

- Added `plusAsBlank` flag to `URIBuilder` to dynamically configure whether '+' should be interpreted as a space in query parameters.
- Implemented `setPlusAsBlank` method to update the flag and re-parse the query accordingly.

Author: arturobernalg

httpcore5/src/main/java/org/apache/hc/core5/net/URIBuilder.java

@@ -88,6 +88,8 @@ public static URIBuilder loopbackAddress() {
     private String fragment;
     private String encodedFragment;
 
+    private boolean plusAsBlank;
+
     /**
      * Constructs an empty instance.
      */
@@ -192,6 +194,33 @@ public Charset getCharset() {
         return charset;
     }
 
+    /**
+     * Sets whether the plus sign ('+') should be interpreted as a blank space (' ') when parsing
+     * the query parameters of the URI.
+     * <p>
+     * In HTTP URLs, query strings may contain spaces encoded as '+' characters or as '%20'.
+     * This flag controls whether '+' is interpreted as a space or remains as a plus sign.
+     * </p>
+     *
+     * <p>
+     * If the query string was already set, calling this method will re-parse the query
+     * using the updated flag. This ensures that the query parameters are processed correctly
+     * based on the specified interpretation of the '+' character.
+     * </p>
+     *
+     * @param plusAsBlank {@code true} to interpret '+' as a space, {@code false} to keep '+' as a literal plus sign.
+     * @return this {@link URIBuilder} instance for method chaining.
+     * @since 5.4
+     */
+    public URIBuilder setPlusAsBlank(final boolean plusAsBlank) {
+        this.plusAsBlank = plusAsBlank;
+        // Re-parse the query string using the updated flag
+        if (this.encodedQuery != null) {
+            this.queryParams = parseQuery(this.encodedQuery, this.charset, this.plusAsBlank);
+        }
+        return this;
+    }
+
     private static final char QUERY_PARAM_SEPARATOR = '&';
     private static final char PARAM_VALUE_SEPARATOR = '=';
     private static final char PATH_SEPARATOR = '/';
@@ -402,7 +431,7 @@ private void digestURI(final URI uri, final Charset charset) {
         this.pathSegments = parsePath(uri.getRawPath(), charset);
         this.pathRootless = uri.getRawPath() == null || !uri.getRawPath().startsWith("/");
         this.encodedQuery = uri.getRawQuery();
-        this.queryParams = parseQuery(uri.getRawQuery(), charset, false);
+        this.queryParams = parseQuery(uri.getRawQuery(), charset, this.plusAsBlank);
         this.encodedFragment = uri.getRawFragment();
         this.fragment = uri.getFragment();
         this.charset = charset;

httpcore5/src/test/java/org/apache/hc/core5/net/TestURIBuilder.java

@@ -973,4 +973,30 @@ void testHttpUriWithEmptyHost() {
                 .setFragment("fragment");
         Assertions.assertThrows(URISyntaxException.class, uribuilder::build);
     }
+
+    @Test
+    void testSetPlusAsBlank() throws Exception {
+        // Case 1: Plus as blank, "+" should be treated as space
+        URIBuilder uriBuilder = new URIBuilder("http://localhost?param=hello+world")
+                .setPlusAsBlank(true);
+        List<NameValuePair> params = uriBuilder.getQueryParams();
+        Assertions.assertEquals("hello world", params.get(0).getValue());
+
+        // Case 2: Plus as plus, "+" should remain "+"
+        uriBuilder = new URIBuilder("http://localhost?param=hello+world")
+                .setPlusAsBlank(false);
+        params = uriBuilder.getQueryParams();
+        Assertions.assertEquals("hello+world", params.get(0).getValue());
+
+        // Case 3: '%20' always interpreted as space
+        uriBuilder = new URIBuilder("http://localhost?param=hello%20world")
+                .setPlusAsBlank(true);
+        params = uriBuilder.getQueryParams();
+        Assertions.assertEquals("hello world", params.get(0).getValue());
+
+        uriBuilder = new URIBuilder("http://localhost?param=hello%20world")
+                .setPlusAsBlank(false);
+        params = uriBuilder.getQueryParams();
+        Assertions.assertEquals("hello world", params.get(0).getValue());
+    }
 }