Changed to use lazy value for credential provider

Author: cenedhryn

core/auth/src/main/java/software/amazon/awssdk/auth/credentials/InstanceProfileCredentialsProvider.java

@@ -89,8 +89,6 @@ public final class InstanceProfileCredentialsProvider
     private final Supplier<ProfileFile> profileFile;
 
     private final String profileName;
-    private final Object lock = new Object();
-    private volatile Boolean isInsecureFallbackDisabled;
 
     /**
      * @see #builder()
@@ -273,14 +271,7 @@ private String handleTokenErrorResponse(Exception e) {
     }
 
     private boolean isInsecureFallbackDisabled() {
-        if (isInsecureFallbackDisabled == null) {
-            synchronized (lock) {
-                if (isInsecureFallbackDisabled == null) {
-                    isInsecureFallbackDisabled = ec2MetadataDisableV1Resolver.resolve();
-                }
-            }
-        }
-        return isInsecureFallbackDisabled;
+        return ec2MetadataDisableV1Resolver.resolve();
     }
 
     private String[] getSecurityCredentials(String imdsHostname, String metadataToken) {

core/auth/src/main/java/software/amazon/awssdk/auth/credentials/internal/Ec2MetadataDisableV1Resolver.java

@@ -21,23 +21,30 @@
 import software.amazon.awssdk.core.SdkSystemSetting;
 import software.amazon.awssdk.profiles.ProfileFile;
 import software.amazon.awssdk.profiles.ProfileProperty;
+import software.amazon.awssdk.utils.Lazy;
 import software.amazon.awssdk.utils.OptionalUtils;
 
 @SdkInternalApi
 public final class Ec2MetadataDisableV1Resolver {
     private final Supplier<ProfileFile> profileFile;
     private final String profileName;
+    private final Lazy<Boolean> resolvedValue;
 
     private Ec2MetadataDisableV1Resolver(Supplier<ProfileFile> profileFile, String profileName) {
         this.profileFile = profileFile;
         this.profileName = profileName;
+        this.resolvedValue = new Lazy<>(this::doResolve);
     }
 
     public static Ec2MetadataDisableV1Resolver create(Supplier<ProfileFile> profileFile, String profileName) {
         return new Ec2MetadataDisableV1Resolver(profileFile, profileName);
     }
 
     public boolean resolve() {
+        return resolvedValue.getValue();
+    }
+
+    public boolean doResolve() {
         return OptionalUtils.firstPresent(fromSystemSettings(),
                                           () -> fromProfileFile(profileFile, profileName))
                             .orElse(false);

core/regions/src/test/java/software/amazon/awssdk/regions/internal/util/EC2MetadataUtilsTest.java

@@ -26,6 +26,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 
 import com.github.tomakehurst.wiremock.client.WireMock;
+import com.github.tomakehurst.wiremock.http.Fault;
 import com.github.tomakehurst.wiremock.junit.WireMockRule;
 import org.junit.Before;
 import org.junit.Rule;