Serialization fix when the expected type is PluginConfigVariable

data-prepper-plugin-framework/src/main/java/org/opensearch/dataprepper/plugin/VariableExpander.java

@@ -57,8 +57,47 @@ public <T> T translate(final JsonParser jsonParser, final Class<T> destinationTy
 
                     })
                     .findFirst()
-                    .orElseGet(() -> objectMapper.convertValue(rawValue, destinationType));
+                    .orElseGet(() -> {
+                        // This change is to support any call
+                        // to validate the secret with a placeholder secret expression like "AWS_SECRET_EXPRESSION"
+                        // which is not of a secrets expression that we would check (filter check above fails) but
+                        // still expects an instance of PluginConfigVariable object returned
+                        if (destinationType.equals(PluginConfigVariable.class)) {
+                            return destinationType.cast(new ImmutablePluginConfigVariable(rawValue));
+                        }
+                        return objectMapper.convertValue(rawValue, destinationType);
+                    });
         }
         return objectMapper.readValue(jsonParser, destinationType);
     }
+
+    private static class ImmutablePluginConfigVariable implements PluginConfigVariable {
+        private final Object rawValue;
+
+        private ImmutablePluginConfigVariable(final Object rawValue) {
+            this.rawValue = rawValue;
+        }
+
+        @Override
+        public Object getValue() {
+            return rawValue;
+        }
+
+        @Override
+        public void setValue(Object updatedValue) {
+            throw new UnsupportedOperationException("ImmutablePluginConfigVariable doesn't support this operation");
+        }
+
+        @Override
+        public void refresh() {
+            // No-op as this is immutable
+            throw new UnsupportedOperationException("ImmutablePluginConfigVariable doesn't support this operation");
+        }
+
+        @Override
+        public boolean isUpdatable() {
+            return false;
+        }
+    }
+
 }

data-prepper-plugin-framework/src/test/java/org/opensearch/dataprepper/plugin/VariableExpanderTest.java

@@ -28,10 +28,14 @@
 import java.util.Collections;
 import java.util.Map;
 import java.util.Set;
+import java.util.UUID;
 import java.util.stream.Stream;
 
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.mockito.ArgumentMatchers.eq;
@@ -177,6 +181,20 @@ public boolean isUpdatable() {
         assertThat(actualResult, equalTo(mockPluginConfigVariable));
     }
 
+    @Test
+    void testTranslateJsonParserWithSPluginConfigVariableValue_when_non_secret_format_is_given() throws IOException {
+        final String testSecretReference = UUID.randomUUID().toString();
+        final JsonParser jsonParser = JSON_FACTORY.createParser(String.format("\"%s\"", testSecretReference));
+        jsonParser.nextToken();
+        objectUnderTest = new VariableExpander(OBJECT_MAPPER, Set.of(pluginConfigValueTranslator));
+        final Object actualResult = objectUnderTest.translate(jsonParser, PluginConfigVariable.class);
+        assertNotNull(actualResult);
+        assertInstanceOf(PluginConfigVariable.class, actualResult);
+        PluginConfigVariable pluginConfigVariableInstance = (PluginConfigVariable) actualResult;
+        assertEquals(testSecretReference, pluginConfigVariableInstance.getValue().toString());
+        assertFalse(pluginConfigVariableInstance.isUpdatable());
+    }
+
     @Test
     void testTranslateJsonParserWithSPluginConfigVariableValue_translate_failure() throws IOException {
         final String testSecretKey = "testSecretKey";