Make Lazy implement Closeable so that it can be closed to close its initializer and value.

Fixes #2149.

Author: millems

.changes/next-release/bugfix-AWSSDKforJavav2-a204bec.json

@@ -0,0 +1,6 @@
+{
+    "type": "bugfix",
+    "category": "AWS SDK for Java v2",
+    "contributor": "",
+    "description": "Fixed a resource leak that could occur when closing the default credentials provider (or a client using the default credentials provider), when `closeable` credentials like STS or SSO were in use. Fixes [#2149](https://github.com/aws/aws-sdk-java-v2/issues/2149)."
+}

core/auth/src/test/java/software/amazon/awssdk/auth/credentials/internal/LazyAwsCredentialsProviderTest.java

@@ -20,6 +20,7 @@
 import org.junit.Test;
 import org.mockito.Mockito;
 import software.amazon.awssdk.auth.credentials.AwsCredentialsProvider;
+import software.amazon.awssdk.utils.SdkAutoCloseable;
 
 public class LazyAwsCredentialsProviderTest {
     @SuppressWarnings("unchecked")
@@ -48,4 +49,30 @@ public void resolveCredentialsInvokesSupplierExactlyOnce() {
         Mockito.verify(credentialsConstructor, Mockito.times(1)).get();
         Mockito.verify(credentials, Mockito.times(2)).resolveCredentials();
     }
+
+    @Test
+    public void delegatesClosesInitializerAndValue() {
+        CloseableSupplier initializer = Mockito.mock(CloseableSupplier.class);
+        CloseableCredentialsProvider value = Mockito.mock(CloseableCredentialsProvider.class);
+
+        Mockito.when(initializer.get()).thenReturn(value);
+
+        LazyAwsCredentialsProvider.create(initializer).close();
+
+        Mockito.verify(initializer).close();
+        Mockito.verify(value).close();
+    }
+
+    @Test
+    public void delegatesClosesInitializerEvenIfGetFails() {
+        CloseableSupplier initializer = Mockito.mock(CloseableSupplier.class);
+        Mockito.when(initializer.get()).thenThrow(new RuntimeException());
+
+        LazyAwsCredentialsProvider.create(initializer).close();
+
+        Mockito.verify(initializer).close();
+    }
+
+    private interface CloseableSupplier extends Supplier<AwsCredentialsProvider>, SdkAutoCloseable {}
+    private interface CloseableCredentialsProvider extends SdkAutoCloseable, AwsCredentialsProvider {}
 }

utils/src/main/java/software/amazon/awssdk/utils/Lazy.java

@@ -20,9 +20,11 @@
 
 /**
  * A class that lazily constructs a value the first time {@link #getValue()} is invoked.
+ *
+ * This should be {@link #close()}d if the initializer returns value that needs to be {@link AutoCloseable#close()}d.
  */
 @SdkPublicApi
-public class Lazy<T> {
+public class Lazy<T> implements SdkAutoCloseable {
     private final Supplier<T> initializer;
 
     private volatile T value;
@@ -53,4 +55,17 @@ public String toString() {
                        .add("value", value == null ? "Uninitialized" : value)
                        .build();
     }
+
+    @Override
+    public void close() {
+        try {
+            // Make sure the value has been initialized before we attempt to close it
+            getValue();
+        } catch (RuntimeException e) {
+            // Failed to initialize the value.
+        }
+
+        IoUtils.closeIfCloseable(initializer, null);
+        IoUtils.closeIfCloseable(value, null);
+    }
 }