fix: isList check in Value checks type of list (#70)

* isList check of Value checks type of list

Signed-off-by: Robert Grassian <[email protected]>

* test for empty list

Signed-off-by: Robert Grassian <[email protected]>

Signed-off-by: Robert Grassian <[email protected]>

Author: rgrassian-split

src/main/java/dev/openfeature/javasdk/Value.java

@@ -125,7 +125,9 @@ public boolean isStructure() {
      * @return boolean
      */
     public boolean isList() {
-        return this.innerObject instanceof List;
+        return this.innerObject instanceof List
+            && (((List) this.innerObject).isEmpty()
+            || ((List) this.innerObject).get(0) instanceof Value);
     }
 
     /** 

src/test/java/dev/openfeature/javasdk/ValueTest.java

@@ -110,4 +110,28 @@ class Something {}
         assertTrue(value.isList());
         assertEquals(ITEM_VALUE, value.asList().get(0).asString());
     }
+
+    @Test public void listMustBeOfValues() {
+        String item = "item";
+        List<String> list = new ArrayList<>();
+        list.add(item);
+        try {
+            new Value((Object) list);
+            fail("Should fail due to creation of list of non-values.");
+        } catch (InstantiationException e) {
+            assertEquals("Invalid value type: class java.util.ArrayList", e.getMessage());
+        }
+    }
+
+    @Test public void emptyListAllowed() {
+        List<String> list = new ArrayList<>();
+        try {
+            Value value = new Value((Object) list);
+            assertTrue(value.isList());
+            List<Value> values = value.asList();
+            assertTrue(values.isEmpty());
+        } catch (Exception e) {
+            fail("Unexpected exception occurred.", e);
+        }
+    }
 }