Fix internal API type

Implicit narrowing conversion in compound assignment
diff --git a/src/changes/changes.xml b/src/changes/changes.xml
index 20c40f9..010cbd8 100644
--- a/src/changes/changes.xml
+++ b/src/changes/changes.xml
@@ -54,6 +54,7 @@
       <action type="fix" dev="ggregory" due-to="Gary Gregory">org.apache.commons.compress.harmony.unpack200.Archive.unpack() should not close streams it does not own (when constructed from Archive(InputStream, JarOutputStream)).</action>
       <action type="fix" dev="ggregory" due-to="takaaki nakama, Gary Gregory">ArArchiveOutputStream doesn't pad correctly when a file name length is odd and greater than 16 (padding missing).</action>
       <action type="fix" issue="COMPRESS-678" dev="ggregory" due-to="Gary Gregory">ArArchiveOutputStream should check that a file name length greater than 16 fits in a header.</action>
+      <action type="fix" dev="ggregory" due-to="Gary Gregory">ArArchiveOutputStream implicit narrowing conversion in compound assignment.</action>
       <!-- UPDATE -->
       <action type="update" dev="ggregory" due-to="Dependabot, Gary Gregory">Bump org.apache.commons:commons-parent from 66 to 69 #495, #508.</action>
       <action type="update" dev="ggregory" due-to="Dependabot, Gary Gregory">Bump org.ow2.asm:asm from 9.6 to 9.7 #504.</action>
diff --git a/src/main/java/org/apache/commons/compress/archivers/ar/ArArchiveOutputStream.java b/src/main/java/org/apache/commons/compress/archivers/ar/ArArchiveOutputStream.java
index 0753f68..c3323a6 100644
--- a/src/main/java/org/apache/commons/compress/archivers/ar/ArArchiveOutputStream.java
+++ b/src/main/java/org/apache/commons/compress/archivers/ar/ArArchiveOutputStream.java
@@ -176,7 +176,7 @@
         entryOffset += len;
     }
 
-    private long write(final String data) throws IOException {
+    private int write(final String data) throws IOException {
         final byte[] bytes = data.getBytes(US_ASCII);
         write(bytes);
         return bytes.length;