fix issue that local span transform failured

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/trace/AbstractTracingSpan.java

@@ -232,11 +232,15 @@ public abstract class AbstractTracingSpan implements AbstractSpan {
         } else {
             spanBuilder.setSpanType(SpanType.Local);
         }
-        spanBuilder.setSpanLayerValue(this.layer.getCode());
+        if (this.layer != null) {
+            spanBuilder.setSpanLayerValue(this.layer.getCode());
+        }
         if (componentId != DictionaryUtil.nullValue()) {
             spanBuilder.setComponentId(componentId);
         } else {
-            spanBuilder.setComponent(componentName);
+            if (componentName != null) {
+                spanBuilder.setComponent(componentName);
+            }
         }
         spanBuilder.setIsError(errorOccurred);
         if (this.tags != null) {

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/context/trace/LocalSpan.java

 package org.skywalking.apm.agent.core.context.trace;
 
-import org.skywalking.apm.network.proto.SpanObject;
-
 /**
  * The <code>LocalSpan</code> represents a normal tracing point, such as a local method.
  *
@@ -29,10 +27,6 @@ public class LocalSpan extends AbstractTracingSpan {
         return this;
     }
 
-    @Override public SpanObject.Builder transform() {
-        return null;
-    }
-
     @Override public boolean isEntry() {
         return false;
     }