Minor fixes, updated docs and changelog

CHANGELOG.asciidoc

@@ -31,6 +31,10 @@ Use subheadings with the "=====" level for adding notes for unreleased changes:
 
 === Unreleased
 
+[float]
+===== Features
+* Context propagation and log correlation now takes place even if recording is disabled - {pull}3358[#3358]
+
 [float]
 ===== Bug fixes
 * Fixed too many spans being created for `HTTPUrlConnection` requests with method `HEAD` - {pull}3353[#3353]

apm-agent-core/src/main/java/co/elastic/apm/agent/impl/ElasticApmTracer.java

@@ -391,7 +391,7 @@ public Span startSpan(AbstractSpan<?> parent, Baggage baggage, long epochMicros)
     public RemoteParentContext createRemoteParentContext() {
         RemoteParentContext ctx = remoteParentContextPool.createInstance();
         while (ctx.getReferenceCount() != 0) {
-            logger.warn("Tried to start a span with a non-zero reference count {} {}", ctx.getReferenceCount(), ctx);
+            logger.warn("Tried to start a remote-context with a non-zero reference count {} {}", ctx.getReferenceCount(), ctx);
             ctx = remoteParentContextPool.createInstance();
         }
         return ctx;

apm-agent-core/src/main/java/co/elastic/apm/agent/impl/TracerConfiguration.java

@@ -35,8 +35,9 @@ public class TracerConfiguration extends ConfigurationOptionProvider {
             "\n" +
             "A boolean specifying if the agent should be recording or not.\n" +
             "When recording, the agent instruments incoming HTTP requests, tracks errors and collects and sends metrics.\n" +
-            "When not recording, the agent works as a noop, not collecting data and not communicating with the APM sever,\n" +
+            "When not recording, the agent works almost as a noop, not collecting data and not communicating with the APM sever,\n" +
             "except for polling the central configuration endpoint.\n" +
+            "Note that trace context propagation, baggage and log correlation remain active even when recording is disabled.\n"+
             "As this is a reversible switch, agent threads are not being killed when inactivated, but they will be \n" +
             "mostly idle in this state, so the overhead should be negligible.\n" +
             "\n" +

apm-agent-core/src/test/java/co/elastic/apm/agent/impl/ElasticApmTracerTest.java

@@ -755,7 +755,7 @@ public AbstractSpan<?> getSpan() {
             return null;
         }
 
-        @org.jetbrains.annotations.Nullable
+        @Nullable
         @Override
         public TraceContext getRemoteParent() {
             return null;

apm-agent-plugins/apm-micrometer-plugin/src/main/java/co/elastic/apm/agent/micrometer/MicrometerMetricsReporter.java

@@ -188,11 +188,9 @@ void run(final long now) {
         for (MeterRegistry registry : currentlyReportableRegistries) {
             registry.forEachMeter(meterConsumer);
         }
-        if(tracer.isRunning()) {
-            logger.debug("Reporting {} meters", meterConsumer.meters.size());
-            for (JsonWriter serializedMetricSet : serializer.serialize(meterConsumer.meters, now * 1000)) {
-                reporter.reportMetrics(serializedMetricSet);
-            }
+        logger.debug("Reporting {} meters", meterConsumer.meters.size());
+        for (JsonWriter serializedMetricSet : serializer.serialize(meterConsumer.meters, now * 1000)) {
+            reporter.reportMetrics(serializedMetricSet);
         }
     }