Merge pull request #415 from elandau/feature/getIfSet

config: Method to get config if it's set without reading properties

ribbon-core/src/main/java/com/netflix/client/config/IClientConfig.java

@@ -18,6 +18,7 @@
 package com.netflix.client.config;
 
 import java.util.Map;
+import java.util.Optional;
 import java.util.function.BiConsumer;
 
 /**
@@ -82,6 +83,9 @@ public interface IClientConfig {
     @Deprecated
 	Object getProperty(IClientConfigKey key, Object defaultVal);
 
+    /**
+     * @deprecated use {@link #getIfSet(IClientConfigKey)}
+     */
     @Deprecated
 	boolean containsProperty(IClientConfigKey key);
 	
@@ -130,6 +134,16 @@ public interface IClientConfig {
         return get(key, key.defaultValue());
     }
 
+    /**
+     * Return a typed property if and only if it was explicitly set, skipping configuration loading.
+     * @param key
+     * @param <T>
+     * @return
+     */
+    default <T> Optional<T> getIfSet(IClientConfigKey<T> key) {
+        return Optional.ofNullable(get(key));
+    }
+
     /**
      * @return Return a global dynamic property not scoped to the specific client.  The property will be looked up as is using the
      * key without any client name or namespace prefix

ribbon-core/src/main/java/com/netflix/client/config/ReloadableClientConfig.java

@@ -240,7 +240,7 @@ public abstract class ReloadableClientConfig implements IClientConfig {
             return value;
         }
 
-        value = resolveDefaultProperty(key);
+        value = getIfSet(key);
         if (value.isPresent()) {
             return value;
         }
@@ -248,7 +248,8 @@ public abstract class ReloadableClientConfig implements IClientConfig {
         return Optional.empty();
     }
 
-    protected <T> Optional<T> resolveDefaultProperty(IClientConfigKey<T> key) {
+    @Override
+    public <T> Optional<T> getIfSet(IClientConfigKey<T> key) {
         return Optional.ofNullable(defaultProperties.get(key.key()))
                 .map(value -> {
                     final Class<T> type = key.type();