XCOMMONS-2448: Multiline value should not be inlined in the XML serializer

xwiki-commons-core/xwiki-commons-filter/xwiki-commons-filter-api/src/test/java/org/xwiki/filter/test/TestFilter.java

@@ -77,4 +77,8 @@
     void onChildWithDefaultValue(@Name("int") @Default("42") int integer,
         @Name("string") @Default("default value") String string, @Name("color") @Default("#ffffff") Color color,
         @Name("map") @Default("") Map<String, String> map);
+
+    void beginContainerWithMultilineParameter(String multi);
+
+    void endContainerWithMultilineParameter(String multi);
 }

xwiki-commons-core/xwiki-commons-filter/xwiki-commons-filter-api/src/test/java/org/xwiki/filter/test/TestFilterImplementation.java

@@ -108,6 +108,18 @@ public void onChildWithDefaultValue(int integer, String string, Color color, Map
 
     }
 
+    @Override
+    public void beginContainerWithMultilineParameter(String multiline)
+    {
+
+    }
+
+    @Override
+    public void endContainerWithMultilineParameter(String multiline)
+    {
+
+    }
+
     // Reserved names
 
     @Override

xwiki-commons-core/xwiki-commons-filter/xwiki-commons-filter-xml/src/main/java/org/xwiki/filter/xml/internal/serializer/DefaultXMLSerializer.java

@@ -142,9 +142,12 @@ private void writeInlineParameters(List<Object> parameters, FilterElementDescrip
 
                     if (attributeName != null) {
                         if (parameterValue instanceof String) {
-                            this.xmlStreamWriter.writeAttribute(attributeName, (String) parameterValue);
+                            // Multiline attributes are really not easy to read
+                            if (!((String) parameterValue).contains("\n")) {
+                                this.xmlStreamWriter.writeAttribute(attributeName, (String) parameterValue);
 
-                            parameters.set(filterParameter.getIndex(), null);
+                                parameters.set(filterParameter.getIndex(), null);
+                            }
                         } else if (XMLUtils.isSimpleType(typeClass)) {
                             this.xmlStreamWriter.writeAttribute(attributeName,
                                 this.converter.<String>convert(String.class, parameterValue));

xwiki-commons-core/xwiki-commons-filter/xwiki-commons-filter-xml/src/test/java/org/xwiki/filter/xml/XMLSerializerFactoryTest.java

@@ -153,6 +153,13 @@ void containerWithMap() throws Exception
             "<containerWithMap><p><_0><entry><string>key</string><int>1</int></entry></_0></p></containerWithMap>");
     }
 
+    @Test
+    void containerWithMultilineParameter() throws Exception
+    {
+        assertParseAndSerialize("<containerWithMultilineParameter><p><multi>line1\n"
+            + "line2</multi></p></containerWithMultilineParameter>");
+    }
+
     @Test
     void customData() throws Exception
     {