Add for Fluent APIs.
MODIFY
src/main/java/org/apache/commons/io/output/ProxyCollectionWriter.java
src/main/java/org/apache/commons/io/output/ProxyCollectionWriter.java
@@ -77,6 +77,7 @@ protected void afterWrite(final int n) throws IOException {
* @throws IOException if an I/O error occurs.
* @since 2.0
*/
+ @SuppressWarnings("resource") // Fluent API.
@Override
public Writer append(final char c) throws IOException {
try {
@@ -96,6 +97,7 @@ public Writer append(final char c) throws IOException {
* @return this writer
* @throws IOException if an I/O error occurs.
*/
+ @SuppressWarnings("resource") // Fluent API.
@Override
public Writer append(final CharSequence csq) throws IOException {
try {
@@ -118,6 +120,7 @@ public Writer append(final CharSequence csq) throws IOException {
* @return this writer
* @throws IOException if an I/O error occurs.
*/
+ @SuppressWarnings("resource") // Fluent API.
@Override
public Writer append(final CharSequence csq, final int start, final int end) throws IOException {
try {

Add @SuppressWarnings("resource") for Fluent APIs.