implementing factory-methods on SimpleOrderedMap

solr/core/src/java/org/apache/solr/request/SimpleFacets.java

@@ -876,7 +876,7 @@ public SimpleOrderedMap<Object> getFacetFieldCounts() throws IOException, Syntax
     String[] facetFs = global.getParams(FacetParams.FACET_FIELD);
 
     if (null == facetFs) {
-      return  SimpleOrderedMap.empty();
+      return  SimpleOrderedMap.of();
     }
 
     // Passing a negative number for FACET_THREADS implies an unlimited number of threads is

solr/solrj/src/java/org/apache/solr/common/util/SimpleOrderedMap.java

@@ -74,7 +74,37 @@ public SimpleOrderedMap<T> clone() {
    * Returns a shared, empty, and immutable instance of SimpleOrderedMap.
    * @return empty SimpleOrderedMap (immutable) 
    */
-  public static SimpleOrderedMap<Object> empty() {
+  public static SimpleOrderedMap<Object> of() {
     return EMPTY;
   }
+
+  /**
+   * Returns an immutable instance of SimpleOrderedMap with a single element.
+   * @return List containing the elements
+   */
+  public static SimpleOrderedMap<Object> of(Object o1) {
+    return new SimpleOrderedMap<>(List.of(o1));
+  }
+
+  /**
+   * Returns an immutable instance of SimpleOrderedMap with two elements.
+   * @return List containing the elements
+   */
+  public static SimpleOrderedMap<Object> of(Object o1, Object o2) {
+    return new SimpleOrderedMap<>(List.of(o1,o2));
+  }
+
+  /**
+   * Returns an immutable instance of SimpleOrderedMap with an arbitrary number of elements. 
+   * @return List containing the elements
+   */
+  public static SimpleOrderedMap<Object> of(Object... elements) {
+	  return switch (elements.length) {
+		  case 0 -> of();
+		  case 1 -> of(elements[0]);
+		  case 2 -> of(elements[0], elements[1]);
+		  default -> new SimpleOrderedMap<>(List.of(elements));
+	  };
+  }
+
 }