feat: minor fix

README.md

@@ -364,4 +364,3 @@ cd library && mvn spotless:apply
 - The File Watchers plugin can format `.java` files on save
 
 - See watcher configuration in [`watcherTasks.xml`](./.idea/watcherTasks.xml)
-

library/src/main/java/com/mastercard/developer/oauth2/http/UserAgent.java

@@ -12,22 +12,28 @@ public final class UserAgent {
     private static final String PRODUCT = "Mastercard-OAuth2-Client";
     private static final String UNKNOWN_VERSION = "0.0.0-unknown";
     private static final String VERSION = readVersionFile();
+    // Cache the user-agent string to avoid rebuilding it on every call
+    private static final String CACHED_USER_AGENT = buildUserAgent();
 
     private UserAgent() {}
 
     /**
-     * Builds a stable user-agent string:
+     * Returns a stable, pre-built user-agent string:
      *   Product/Version (Runtime; OS [OS Version])
      * Example:
      *   Mastercard-OAuth2-Client/1.0.0 (Java/17.0.2; Linux 5.15)
      */
     public static String get() {
+        return CACHED_USER_AGENT;
+    }
+
+    private static String buildUserAgent() {
         String javaVer = System.getProperty("java.version", "unknown");
         String osName = System.getProperty("os.name", "unknown");
         String osVer = System.getProperty("os.version", "").trim();
-        var runtime = "Java/" + javaVer;
+        String runtime = "Java/" + javaVer;
         String osPart = osName + (osVer.isEmpty() ? "" : " " + osVer);
-        return String.format("%s/%s (%s; %s)", PRODUCT, VERSION, runtime, osPart);
+        return PRODUCT + "/" + VERSION + " (" + runtime + "; " + osPart + ")";
     }
 
     private static String readVersionFile() {

library/src/main/java/com/mastercard/developer/oauth2/internal/json/GsonJsonProvider.java

@@ -1,6 +1,7 @@
 package com.mastercard.developer.oauth2.internal.json;
 
 import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
 import com.google.gson.reflect.TypeToken;
 import com.mastercard.developer.oauth2.internal.json.exception.OAuth2ClientJsonException;
 import java.lang.reflect.Type;
@@ -9,13 +10,18 @@
 
 public class GsonJsonProvider implements JsonProvider {
 
-    private static final Gson gson = new Gson();
+    // Use a configured Gson instance and cache the Map type to avoid allocating a new TypeToken on each parse.
+    private static final Gson gson = new GsonBuilder()
+        .disableHtmlEscaping()
+        .serializeNulls()
+        .create();
+
+    private static final Type MAP_TYPE = new TypeToken<Map<String, Object>>() {}.getType();
 
     @Override
     public Map<String, Object> parse(String json) throws OAuth2ClientJsonException {
         try {
-            Type type = new TypeToken<Map<String, Object>>() {}.getType();
-            return gson.fromJson(json, type);
+            return gson.fromJson(json, MAP_TYPE);
         } catch (Exception e) {
             throw new OAuth2ClientJsonException("Failed to read JSON", e);
         }

library/src/main/java/com/mastercard/developer/oauth2/internal/json/JacksonJsonProvider.java

@@ -10,11 +10,13 @@ public class JacksonJsonProvider implements JsonProvider {
 
     private static final ObjectMapper mapper = new ObjectMapper();
 
+    // Cache the TypeReference to avoid creating a new anonymous subclass on each parse call.
+    private static final TypeReference<Map<String, Object>> MAP_TYPE_REFERENCE = new TypeReference<Map<String, Object>>() {};
+
     @Override
     public Map<String, Object> parse(String json) throws OAuth2ClientJsonException {
         try {
-            var typeReference = new TypeReference<Map<String, Object>>() {};
-            return mapper.readValue(json, typeReference);
+            return mapper.readValue(json, MAP_TYPE_REFERENCE);
         } catch (Exception e) {
             throw new OAuth2ClientJsonException("Failed to read JSON", e);
         }

library/src/test/java/com/mastercard/developer/oauth2/test/fixtures/BaseClientTest.java

@@ -11,7 +11,9 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Named;
 import org.junit.jupiter.api.extension.RegisterExtension;
+import org.junit.jupiter.api.function.ThrowingSupplier;
 import org.junit.jupiter.params.provider.Arguments;
+import org.opentest4j.TestAbortedException;
 
 public abstract class BaseClientTest extends BaseTest {
 
@@ -68,63 +70,27 @@ protected static Stream<Arguments> serverAndKeyProvider() {
     }
 
     protected static TestConfig getMastercardConfig() {
-        try {
-            return TestConfig.getMastercardApiConfig();
-        } catch (IllegalStateException e) {
-            throw e;
-        } catch (Exception e) {
-            throw new IllegalStateException(e);
-        }
+        return runOrWrap(TestConfig::getMastercardApiConfig);
     }
 
     private static TestConfig getMastercardConfigWithEcKey() {
-        try {
-            return TestConfig.getMastercardApiConfig(StaticKeys.EC_KEY_PAIR);
-        } catch (IllegalStateException e) {
-            throw e;
-        } catch (Exception e) {
-            throw new IllegalStateException(e);
-        }
+        return runOrWrap(() -> TestConfig.getMastercardApiConfig(StaticKeys.EC_KEY_PAIR));
     }
 
     private static TestConfig getMastercardConfigWithRsaKey() {
-        try {
-            return TestConfig.getMastercardApiConfig(StaticKeys.RSA_KEY_PAIR);
-        } catch (IllegalStateException e) {
-            throw e;
-        } catch (Exception e) {
-            throw new IllegalStateException(e);
-        }
+        return runOrWrap(() -> TestConfig.getMastercardApiConfig(StaticKeys.RSA_KEY_PAIR));
     }
 
     protected static TestConfig getFakeConfig() {
-        try {
-            return TestConfig.getFakeApiConfig(authorizationServer, resourceServer);
-        } catch (IllegalStateException e) {
-            throw e;
-        } catch (Exception e) {
-            throw new IllegalStateException(e);
-        }
+        return runOrWrap(() -> TestConfig.getFakeApiConfig(authorizationServer, resourceServer));
     }
 
     private static TestConfig getFakeConfigWithEcKey() {
-        try {
-            return TestConfig.getFakeApiConfig(authorizationServer, resourceServer, StaticKeys.EC_KEY_PAIR);
-        } catch (IllegalStateException e) {
-            throw e;
-        } catch (Exception e) {
-            throw new IllegalStateException(e);
-        }
+        return runOrWrap(() -> TestConfig.getFakeApiConfig(authorizationServer, resourceServer, StaticKeys.EC_KEY_PAIR));
     }
 
     private static TestConfig getFakeConfigWithRsaKey() {
-        try {
-            return TestConfig.getFakeApiConfig(authorizationServer, resourceServer, StaticKeys.RSA_KEY_PAIR);
-        } catch (IllegalStateException e) {
-            throw e;
-        } catch (Exception e) {
-            throw new IllegalStateException(e);
-        }
+        return runOrWrap(() -> TestConfig.getFakeApiConfig(authorizationServer, resourceServer, StaticKeys.RSA_KEY_PAIR));
     }
 
     private static Arguments createConfigArgument(String name, Supplier<TestConfig> configSupplier) {
@@ -135,4 +101,14 @@ protected static String readResourceId(String resource) throws OAuth2ClientJsonE
         Map<String, Object> jsonMap = JsonProvider.getInstance().parse(resource);
         return (String) jsonMap.get("id");
     }
+
+    private static <T> T runOrWrap(ThrowingSupplier<T> action) {
+        try {
+            return action.get();
+        } catch (TestAbortedException | IllegalStateException e) {
+            throw e;
+        } catch (Throwable e) {
+            throw new IllegalStateException(e);
+        }
+    }
 }

library/src/test/java/com/mastercard/developer/oauth2/test/fixtures/TestConfig.java

@@ -1,5 +1,7 @@
 package com.mastercard.developer.oauth2.test.fixtures;
 
+import static org.junit.jupiter.api.Assumptions.assumeTrue;
+
 import com.mastercard.developer.oauth2.config.OAuth2Config;
 import com.mastercard.developer.oauth2.config.SecurityProfile;
 import com.mastercard.developer.oauth2.core.dpop.StaticDPoPKeyProvider;
@@ -51,14 +53,19 @@ public static TestConfig getMastercardApiConfig(KeyPair dpopKeyPair) throws Exce
         String readScopes = getEnv("READ_SCOPES");
         String writeScopes = getEnv("WRITE_SCOPES");
 
-        validateEnvVariable("PRIVATE_KEY", privateKeyContent);
-        validateEnvVariable("CLIENT_ID", clientId);
-        validateEnvVariable("KID", kid);
-        validateEnvVariable("TOKEN_ENDPOINT", tokenEndpoint);
-        validateEnvVariable("ISSUER", issuer);
-        validateEnvVariable("API_BASE_URL", apiBaseUrlEnv);
-        validateEnvVariable("READ_SCOPES", readScopes);
-        validateEnvVariable("WRITE_SCOPES", readScopes);
+        try {
+            validateEnvVariable("PRIVATE_KEY", privateKeyContent);
+            validateEnvVariable("CLIENT_ID", clientId);
+            validateEnvVariable("KID", kid);
+            validateEnvVariable("TOKEN_ENDPOINT", tokenEndpoint);
+            validateEnvVariable("ISSUER", issuer);
+            validateEnvVariable("API_BASE_URL", apiBaseUrlEnv);
+            validateEnvVariable("READ_SCOPES", readScopes);
+            validateEnvVariable("WRITE_SCOPES", readScopes);
+        } catch (Exception e) {
+            // Disable the calling test when environment variables are missing
+            assumeTrue(false, "Test disabled: %s".formatted(e.getMessage()));
+        }
 
         OAuth2Config oauth2Config = OAuth2Config.builder()
             .securityProfile(SecurityProfile.FAPI2SP_PRIVATE_KEY_DPOP)