fix: flush reporter instead of closing

src/Jaeger/Jaeger.php

@@ -270,7 +270,7 @@ public function gen128bit(): void
     public function flush(): void
     {
         $this->reportSpan();
-        $this->reporter->close();
+        $this->reporter->flush();
     }
 
     private function generateId(): string

src/Jaeger/Reporter/NullReporter.php

@@ -24,6 +24,11 @@ public function report(Jaeger $jaeger)
         // no-op
     }
 
+    public function flush()
+    {
+        // no-op
+    }
+
     public function close()
     {
         // no-op

src/Jaeger/Reporter/RemoteReporter.php

@@ -35,6 +35,11 @@ public function report(Jaeger $jaeger)
         $this->tran->append($jaeger);
     }
 
+    public function flush()
+    {
+        $this->tran->flush();
+    }
+
     public function close()
     {
         $this->tran->close();

src/Jaeger/Reporter/Reporter.php

@@ -21,5 +21,7 @@ interface Reporter
 {
     public function report(Jaeger $jaeger);
 
+    public function flush();
+
     public function close();
 }

src/Jaeger/SpanContext.php

@@ -71,6 +71,8 @@ public function withBaggageItem(string $key, string $value): \OpenTracing\SpanCo
 
     /**
      * {@inheritdoc}
+     *
+     * @return \Traversable
      */
     public function getIterator()
     {