[javadoc] add missing space

Bug: 348323500
Test: presubmit

Change-Id: Iacad7bd2537108425cc9dedcfdd3eeef7f9765b8
diff --git a/thread/framework/java/android/net/thread/ThreadNetworkController.java b/thread/framework/java/android/net/thread/ThreadNetworkController.java
index 1222398..f716f98 100644
--- a/thread/framework/java/android/net/thread/ThreadNetworkController.java
+++ b/thread/framework/java/android/net/thread/ThreadNetworkController.java
@@ -368,7 +368,7 @@
          *     0-9 of user-input friendly length (typically 9), or {@code null} if {@code
          *     ephemeralKeyState} is {@link #EPHEMERAL_KEY_DISABLED} or the caller doesn't have the
          *     permission {@link android.permission.THREAD_NETWORK_PRIVILEGED}
-         * @param expiry a timestamp of when the ephemeral key will expireor {@code null} if {@code
+         * @param expiry a timestamp of when the ephemeral key will expire or {@code null} if {@code
          *     ephemeralKeyState} is {@link #EPHEMERAL_KEY_DISABLED}
          */
         @FlaggedApi(Flags.FLAG_EPSKC_ENABLED)