add support for custom classloaders in the default configuration

Author: aivinog1

keycloak/src/main/java/com/avast/grpc/jwt/keycloak/KeycloakFactory.java

@@ -6,11 +6,15 @@
 import org.keycloak.admin.client.KeycloakBuilder;
 
 public final class KeycloakFactory {
-  public static Config DefaultConfig =
-      ConfigFactory.defaultReference().getConfig("keycloakDefaults");
+
+  public static final String KEYCLOAK_DEFAULTS_CONFIG_NAME = "keycloakDefaults";
 
   public static Keycloak fromConfig(Config config) {
-    Config fc = config.withFallback(DefaultConfig);
+    return fromConfig(config, Thread.currentThread().getContextClassLoader());
+  }
+
+  public static Keycloak fromConfig(Config config, ClassLoader contextClassLoader) {
+    Config fc = config.withFallback(getDefaultConfig(contextClassLoader));
     return KeycloakBuilder.builder()
         .clientId(fc.getString("clientId"))
         .clientSecret(fc.getString("clientSecret"))
@@ -22,5 +26,9 @@ public static Keycloak fromConfig(Config config) {
         .build();
   }
 
+  public static Config getDefaultConfig(final ClassLoader classLoader) {
+    return ConfigFactory.defaultReference(classLoader).getConfig(KEYCLOAK_DEFAULTS_CONFIG_NAME);
+  }
+
   private KeycloakFactory() {}
 }

keycloak/src/main/java/com/avast/grpc/jwt/keycloak/server/KeycloakJwtServerInterceptor.java

@@ -1,6 +1,6 @@
 package com.avast.grpc.jwt.keycloak.server;
 
-import static com.avast.grpc.jwt.keycloak.KeycloakFactory.DefaultConfig;
+import static com.avast.grpc.jwt.keycloak.KeycloakFactory.getDefaultConfig;
 
 import com.avast.grpc.jwt.server.JwtServerInterceptor;
 import com.avast.grpc.jwt.server.JwtTokenParser;
@@ -14,7 +14,12 @@ public KeycloakJwtServerInterceptor(JwtTokenParser<AccessToken> tokenParser) {
   }
 
   public static KeycloakJwtServerInterceptor fromConfig(Config config) {
-    Config fc = config.withFallback(DefaultConfig);
+    return fromConfig(config, Thread.currentThread().getContextClassLoader());
+  }
+
+  public static KeycloakJwtServerInterceptor fromConfig(
+      Config config, ClassLoader contextClassLoader) {
+    Config fc = config.withFallback(getDefaultConfig(contextClassLoader));
     KeycloakPublicKeyProvider publicKeyProvider =
         new DefaultKeycloakPublicKeyProvider(
             fc.getString("serverUrl"),