add missing warning about discarded value (#7821)

Author: zeitlinger

sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/fileconfig/YamlDeclarativeConfigProperties.java

@@ -175,6 +175,9 @@ public Integer getInt(String name) {
     if (value instanceof Long) {
       return ((Long) value).intValue();
     }
+    if (value != null) {
+      logTypeWarning(name, value, Integer.class);
+    }
     return null;
   }