Retain behaviour on null resource

Keep returning an empty resource if incoming resource is null.

Signed-off-by: Karsten Schnitter <k.schnitter@sap.com>

Author: KarstenSchnitter

cf-java-logging-support-opentelemetry-agent-extension/src/main/java/com/sap/hcf/cf/logging/opentelemetry/agent/ext/attributes/CloudFoundryResourceCustomizer.java

@@ -38,7 +38,12 @@ public Resource apply(Resource resource, ConfigProperties configProperties) {
             return Resource.empty();
         }
 
-        if (resource == null || resource.getAttributes().isEmpty()) {
+        if (resource == null) {
+            LOG.config("Not running in CF. Cannot obtain CF resource.");
+            return Resource.empty();
+        }
+
+        if (resource.getAttributes().isEmpty()) {
             LOG.config("Not running in CF. Cannot obtain CF resource attributes.");
             return resource;
         }

cf-java-logging-support-opentelemetry-agent-extension/src/test/java/com/sap/hcf/cf/logging/opentelemetry/agent/ext/attributes/CloudFoundryResourceCustomizerTest.java

@@ -20,6 +20,13 @@ public class CloudFoundryResourceCustomizerTest {
                     .put("cloudfoundry.process.type", "test-process-type").put("cloudfoundry.space.id", "test-space-id")
                     .put("cloudfoundry.space.name", "test-space").build();
 
+    @Test
+    void emptyResourceWithNullResource() {
+        CloudFoundryResourceCustomizer customizer = new CloudFoundryResourceCustomizer();
+        Resource resource = customizer.apply(null, DefaultConfigProperties.create(new HashMap<>()));
+        assertTrue(resource.getAttributes().isEmpty());
+    }
+
     @Test
     void emptyResourceWhenNotInCf() {
         CloudFoundryResourceCustomizer customizer = new CloudFoundryResourceCustomizer();