Support merge nested Map in list for JIRA configurations (#37634)

This commit allows JIRA API fields that require a list of key/value 
pairs (maps), such as JIRA "components" to use use template snippets 
(e.g. {{ctx.payload.foo}}). Prior to this change the templated value 
(not the de-referenced value) would be sent via the API and error. 

Closes #30068

x-pack/plugin/watcher/src/main/java/org/elasticsearch/xpack/watcher/actions/jira/ExecutableJiraAction.java

@@ -88,6 +88,8 @@ static Map<String, Object> merge(final Map<String, Object> fields, final Map<Str
                     for (Object v : (List) value) {
                         if (v instanceof String) {
                             newValues.add(fn.apply((String) v));
+                        } else if (v instanceof Map) {
+                            newValues.add(merge(new HashMap<>(), (Map<String, ?>) v, fn));
                         } else {
                             newValues.add(v);
                         }

x-pack/plugin/watcher/src/test/java/org/elasticsearch/xpack/watcher/actions/jira/ExecutableJiraActionTests.java

@@ -27,9 +27,11 @@
 import org.joda.time.DateTimeZone;
 import org.mockito.ArgumentCaptor;
 
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.function.Function;
@@ -311,4 +313,54 @@ public String render(TextTemplate textTemplate, Map<String, Object> model) {
             return textTemplate.getTemplate().toUpperCase(Locale.ROOT);
         }
     }
+
+    public void testMerge() {
+        Map<String, Object> writeableMap = new HashMap<>();
+        Map<String, Object> mergeNull = ExecutableJiraAction.merge(writeableMap, null, s -> s);
+        assertTrue(mergeNull.isEmpty());
+        Map<String, Object> map = new HashMap<>();
+        map.put("foo", "bar");
+        map.put("list", Arrays.asList("test1", "test2"));
+        Map<String, Object> valueMap = new HashMap<>();
+        valueMap.put("var", "abc");
+        map.put("map", valueMap);
+        Map<String, Object> componentMap = new HashMap<>();
+        componentMap.put("name", "value");
+        List<Map<String, Object>> list = new ArrayList<>();
+        list.add(componentMap);
+        map.put("components", list);
+        Map<String, Object> result = ExecutableJiraAction.merge(writeableMap, map, s -> s.toUpperCase(Locale.ROOT));
+        assertThat(result, hasEntry("FOO", "BAR"));
+        assertThat(result.get("LIST"), instanceOf(List.class));
+        List<String> mergedList = (List<String>) result.get("LIST");
+        assertEquals(2, mergedList.size());
+        assertEquals("TEST1", mergedList.get(0));
+        assertEquals("TEST2", mergedList.get(1));
+        Map<String, Object> mergedMap = (Map<String, Object>) result.get("MAP");
+        assertEquals(1, mergedMap.size());
+        assertEquals("ABC", mergedMap.get("VAR"));
+        assertThat(result.get("COMPONENTS"), instanceOf(List.class));
+        List<Map<String, Object>> components = (List<Map<String, Object>>) result.get("COMPONENTS");
+        assertThat(components.get(0), hasEntry("NAME", "VALUE"));
+
+        // test the fields is not overwritten
+        Map<String, Object> fields = new HashMap<>();
+        fields.put("FOO", "bob");
+        fields.put("LIST", Arrays.asList("test3"));
+        fields.put("MAP", new HashMap<>());
+        fields.put("COMPONENTS", new ArrayList<>());
+
+        result = ExecutableJiraAction.merge(fields, map, s -> s.toUpperCase(Locale.ROOT));
+        assertThat(result, hasEntry("FOO", "bob"));
+        assertThat(result.get("LIST"), instanceOf(List.class));
+        mergedList = (List<String>) result.get("LIST");
+        assertEquals(1, mergedList.size());
+        assertEquals("test3", mergedList.get(0));
+        mergedMap = (Map<String, Object>) result.get("MAP");
+        assertTrue(mergedMap.isEmpty());
+        assertThat(result.get("COMPONENTS"), instanceOf(List.class));
+        components = (List<Map<String, Object>>) result.get("COMPONENTS");
+        assertTrue(components.isEmpty());
+    }
+
 }