Use ZoneId instead of String for timezone related configuration

core/deployment/src/main/java/io/quarkus/deployment/builditem/ObjectSubstitutionBuildItem.java

@@ -30,8 +30,9 @@ public Holder(Class<F> from, Class<T> to, Class<ObjectSubstitution<F, T>> substi
 
     public final Holder<?, ?> holder;
 
-    public <F, T> ObjectSubstitutionBuildItem(Class<F> from, Class<T> to, Class<ObjectSubstitution<F, T>> substitution) {
-        holder = new Holder<>(from, to, substitution);
+    public <F, T> ObjectSubstitutionBuildItem(Class<F> from, Class<T> to,
+            Class<? extends ObjectSubstitution<F, T>> substitution) {
+        holder = new Holder(from, to, substitution);
     }
 
     public ObjectSubstitutionBuildItem(Holder<?, ?> holder) {

core/deployment/src/main/java/io/quarkus/deployment/recording/substitutions/AdditionalSubstitutionsBuildStep.java

@@ -0,0 +1,33 @@
+package io.quarkus.deployment.recording.substitutions;
+
+import java.time.ZoneId;
+
+import io.quarkus.deployment.annotations.BuildProducer;
+import io.quarkus.deployment.annotations.BuildStep;
+import io.quarkus.deployment.builditem.ObjectSubstitutionBuildItem;
+
+public class AdditionalSubstitutionsBuildStep {
+
+    @BuildStep
+    public void additionalSubstitutions(BuildProducer<ObjectSubstitutionBuildItem> producer) {
+        zoneIdSubstitutions(producer);
+    }
+
+    @SuppressWarnings("unchecked")
+    private void zoneIdSubstitutions(BuildProducer<ObjectSubstitutionBuildItem> producer) {
+        try {
+            /*
+             * We can't refer to these classes as they are package private but we need a handle on need
+             * because the bytecode recorder needs to have the actual class registered and not a super class
+             */
+
+            Class<ZoneId> zoneRegionClass = (Class<ZoneId>) Class.forName("java.time.ZoneRegion");
+            producer.produce(new ObjectSubstitutionBuildItem(zoneRegionClass, String.class, ZoneIdSubstitution.class));
+
+            Class<ZoneId> zoneOffsetClass = (Class<ZoneId>) Class.forName("java.time.ZoneRegion");
+            producer.produce(new ObjectSubstitutionBuildItem(zoneOffsetClass, String.class, ZoneIdSubstitution.class));
+        } catch (ClassNotFoundException e) {
+            throw new IllegalStateException("Improper registration of ZoneId substitution", e);
+        }
+    }
+}

core/deployment/src/main/java/io/quarkus/deployment/recording/substitutions/ZoneIdSubstitution.java

@@ -0,0 +1,18 @@
+package io.quarkus.deployment.recording.substitutions;
+
+import java.time.ZoneId;
+
+import io.quarkus.runtime.ObjectSubstitution;
+
+public class ZoneIdSubstitution implements ObjectSubstitution<ZoneId, String> {
+
+    @Override
+    public String serialize(ZoneId obj) {
+        return obj.getId();
+    }
+
+    @Override
+    public ZoneId deserialize(String str) {
+        return ZoneId.of(str);
+    }
+}

core/runtime/src/main/java/io/quarkus/runtime/configuration/ZoneIdConverter.java

@@ -0,0 +1,24 @@
+package io.quarkus.runtime.configuration;
+
+import static io.quarkus.runtime.configuration.ConverterSupport.DEFAULT_QUARKUS_CONVERTER_PRIORITY;
+
+import java.io.Serializable;
+import java.time.ZoneId;
+
+import javax.annotation.Priority;
+
+import org.eclipse.microprofile.config.spi.Converter;
+
+/**
+ * A converter to support locales.
+ */
+@Priority(DEFAULT_QUARKUS_CONVERTER_PRIORITY)
+public class ZoneIdConverter implements Converter<ZoneId>, Serializable {
+
+    private static final long serialVersionUID = -439010527617997936L;
+
+    @Override
+    public ZoneId convert(final String value) {
+        return ZoneId.of(value);
+    }
+}

extensions/jackson/deployment/src/main/java/io/quarkus/jackson/deployment/JacksonProcessor.java

@@ -7,7 +7,6 @@
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
-import java.util.TimeZone;
 
 import javax.inject.Inject;
 import javax.inject.Singleton;
@@ -179,23 +178,6 @@ private void registerModuleIfOnClassPath(String moduleClassName,
     @Record(ExecutionTime.STATIC_INIT)
     SyntheticBeanBuildItem pushConfigurationBean(JacksonRecorder jacksonRecorder,
             JacksonBuildTimeConfig jacksonBuildTimeConfig) {
-
-        if (jacksonBuildTimeConfig.timezone.isPresent()) {
-            /*
-             * We need to make timezone a String instead of a java.util.TimeZone class
-             * because:
-             * 1) TimeZone cannot automatically be handled by the BytecodeRecorder
-             * 2) Handling it would require us to add non-JDK classes (i.e. sun.util.calendar.ZoneInfo) to bytecode recording
-             */
-            String timeZoneStr = jacksonBuildTimeConfig.timezone.get();
-            TimeZone timeZone = TimeZone.getTimeZone(timeZoneStr);
-            if ("GMT".equals(timeZone.getID()) && !timeZoneStr.startsWith("GMT")) {
-                // Parsing an illegal TZ string value results in falling back to GMT...
-                throw new IllegalArgumentException(
-                        "Value '" + timeZoneStr + "' is an invalid value for the 'quarkus.jackson.timezone' property");
-            }
-        }
-
         return SyntheticBeanBuildItem.configure(JacksonConfigSupport.class)
                 .scope(Singleton.class)
                 .supplier(jacksonRecorder.jacksonConfigSupport(jacksonBuildTimeConfig))

extensions/jackson/runtime/src/main/java/io/quarkus/jackson/runtime/JacksonBuildTimeConfig.java

@@ -1,5 +1,6 @@
 package io.quarkus.jackson.runtime;
 
+import java.time.ZoneId;
 import java.util.Optional;
 
 import io.quarkus.runtime.annotations.ConfigItem;
@@ -28,5 +29,5 @@ public class JacksonBuildTimeConfig {
      * If not set, Jackson will use its own default.
      */
     @ConfigItem
-    public Optional<String> timezone;
+    public Optional<ZoneId> timezone;
 }

extensions/jackson/runtime/src/main/java/io/quarkus/jackson/runtime/JacksonConfigSupport.java

@@ -1,14 +1,16 @@
 package io.quarkus.jackson.runtime;
 
+import java.time.ZoneId;
+
 public class JacksonConfigSupport {
 
     private final boolean failOnUnknownProperties;
 
     private final boolean writeDatesAsTimestamps;
 
-    private final String timeZone;
+    private final ZoneId timeZone;
 
-    public JacksonConfigSupport(boolean failOnUnknownProperties, boolean writeDatesAsTimestamps, String timeZone) {
+    public JacksonConfigSupport(boolean failOnUnknownProperties, boolean writeDatesAsTimestamps, ZoneId timeZone) {
         this.failOnUnknownProperties = failOnUnknownProperties;
         this.writeDatesAsTimestamps = writeDatesAsTimestamps;
         this.timeZone = timeZone;
@@ -22,7 +24,7 @@ public boolean isWriteDatesAsTimestamps() {
         return writeDatesAsTimestamps;
     }
 
-    public String getTimeZone() {
+    public ZoneId getTimeZone() {
         return timeZone;
     }
 }

extensions/jackson/runtime/src/main/java/io/quarkus/jackson/runtime/ObjectMapperProducer.java

@@ -1,5 +1,6 @@
 package io.quarkus.jackson.runtime;
 
+import java.time.ZoneId;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -34,10 +35,9 @@ public ObjectMapper objectMapper(Instance<ObjectMapperCustomizer> customizers,
             // this feature is enabled by default, so we disable it
             objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
         }
-        String timeZoneStr = jacksonConfigSupport.getTimeZone();
-        if (timeZoneStr != null) {
-            TimeZone timeZone = TimeZone.getTimeZone(timeZoneStr);
-            objectMapper.setTimeZone(timeZone);
+        ZoneId zoneId = jacksonConfigSupport.getTimeZone();
+        if (zoneId != null) {
+            objectMapper.setTimeZone(TimeZone.getTimeZone(zoneId));
         }
         List<ObjectMapperCustomizer> sortedCustomizers = sortCustomizersInDescendingPriorityOrder(customizers);
         for (ObjectMapperCustomizer customizer : sortedCustomizers) {

integration-tests/container-image/quarkus-standard-way/src/test/java/io/quarkus/it/container/image/GreetingResourceIT.java

@@ -3,12 +3,11 @@
 import static io.restassured.RestAssured.given;
 import static org.hamcrest.CoreMatchers.is;
 
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
 import io.quarkus.test.junit.QuarkusIntegrationTest;
 
-@Disabled("This test seems flaky")
+//@Disabled("This test seems flaky")
 @QuarkusIntegrationTest
 public class GreetingResourceIT {