Remove the fallback to URLConnection when SSL is disabled for REST Client

The fallback was originally added to get around limitation in Apache HTTP Client
when SSL is completely disabled in native binaries.
However we can get around these limitations in a more elegant manner in Quarkus
(see quarkusio/quarkus#9773).
By defaulting to Apache HTTP Client, things like HTTP Patch can be supported
OOTB (see quarkusio/quarkus#9342).

Author: geoand

resteasy-client-microprofile/src/main/java/org/jboss/resteasy/microprofile/client/RestClientBuilderImpl.java

@@ -67,13 +67,8 @@ public class RestClientBuilderImpl implements RestClientBuilder {
     public static final MethodInjectionFilter METHOD_INJECTION_FILTER = new MethodInjectionFilter();
     public static final ClientHeadersRequestFilter HEADERS_REQUEST_FILTER = new ClientHeadersRequestFilter();
 
-    static boolean SSL_ENABLED = true;
     static ResteasyProviderFactory PROVIDER_FACTORY;
 
-    public static void setSslEnabled(boolean enabled) {
-        SSL_ENABLED = enabled;
-    }
-
     public static void setProviderFactory(ResteasyProviderFactory providerFactory) {
         PROVIDER_FACTORY = providerFactory;
     }
@@ -260,13 +255,12 @@ public <T> T build(Class<T> aClass) throws IllegalStateException, RestClientDefi
             resteasyClientBuilder.connectTimeout(connectTimeout, connectTimeoutUnit);
         }
 
-        if (!SSL_ENABLED) {
+        if (useURLConnection()) {
             resteasyClientBuilder.httpEngine(new URLConnectionClientEngineBuilder().resteasyClientBuilder(resteasyClientBuilder).build());
             resteasyClientBuilder.sslContext(null);
             resteasyClientBuilder.trustStore(null);
             resteasyClientBuilder.keyStore(null, "");
         }
-
         client = resteasyClientBuilder
                 .build();
         client.register(AsyncInterceptorRxInvokerProvider.class);
@@ -287,6 +281,19 @@ public <T> T build(Class<T> aClass) throws IllegalStateException, RestClientDefi
         return proxy;
     }
 
+    /**
+     * Determines whether or not to default to using the URLConnection instead of the Apache HTTP Client.
+     * If the {@code org.jboss.resteasy.microprofile.defaultToURLConnectionHttpClient} system property is {@code true},
+     * then this method returns {@code true}. In all other cases it returns {@code false}
+     */
+    private boolean useURLConnection() {
+        if (useURLConnection == null) {
+            String defaultToURLConnection = System.getProperty("org.jboss.resteasy.microprofile.defaultToURLConnectionHttpClient", "false");
+            useURLConnection = defaultToURLConnection.toLowerCase().equals("true");
+        }
+        return useURLConnection;
+    }
+
     private Optional<InetSocketAddress> selectHttpProxy() {
         return ProxySelector.getDefault().select(baseURI).stream()
                 .filter(proxy -> proxy.type() == java.net.Proxy.Type.HTTP)
@@ -622,6 +629,7 @@ ResteasyClientBuilder getBuilderDelegate() {
     private KeyStore keyStore;
     private String keystorePassword;
     private HostnameVerifier hostnameVerifier;
+    private Boolean useURLConnection;
 
 
     private Set<Object> localProviderInstances = new HashSet<>();