chore!: drop "timer" option to startTransaction/startSpan

CHANGELOG4.asciidoc

@@ -10,6 +10,10 @@
   Users of earlier Node.js versions can use elastic-apm-node v3.x, which
   supports back to Node.js v8.6.
 
+* Ignore a `timer` option passed to `startTransaction()` and `startSpan()` APIs.
+  This option was never documented. It would be surprising if any user is
+  impacted by this.
+
 * Remove long deprecated support for the `ELASTIC_APM_`-prefixed environment
   variables for the <<kubernetes-node-name,Kubernetes config options>>. For
   example, one must use `KUBERNETES_POD_NAME` and not

lib/instrumentation/span.js

@@ -34,11 +34,8 @@ function Span(transaction, ...args) {
   const [name, ...tsaArgs] = args; // "tsa" === Type, Subtype, Action
 
   if (opts.timer) {
-    process.emitWarning(
-      'specifying the `timer` option to `new Span()` was never a public API and will be removed',
-      'DeprecationWarning',
-      'ELASTIC_APM_SPAN_TIMER_OPTION',
-    );
+    // Before 4.x this option could be passed in. It was never publicly documented.
+    delete opts.timer;
   }
   if (!opts.childOf) {
     const defaultChildOf =

lib/instrumentation/transaction.js

@@ -53,11 +53,8 @@ function Transaction(agent, name, ...args) {
     typeof args[args.length - 1] === 'object' ? args.pop() || {} : {};
 
   if (opts.timer) {
-    process.emitWarning(
-      'specifying the `timer` option to `new Transaction()` was never a public API and will be removed',
-      'DeprecationWarning',
-      'ELASTIC_APM_SPAN_TIMER_OPTION',
-    );
+    // Before 4.x this option could be passed in. It was never publicly documented.
+    delete opts.timer;
   }
   if (opts.tracestate) {
     opts.tracestate = TraceState.fromStringFormatString(opts.tracestate);