Support for Targeted Property Refresh in /actuator/refresh Endpoint

Fixes spring-cloud#1370

spring-cloud-context/src/main/java/org/springframework/cloud/context/refresh/ContextRefresher.java

@@ -90,10 +90,13 @@ protected RefreshScope getScope() {
 		return this.scope;
 	}
 
-	public synchronized Set<String> refresh() {
-		Set<String> keys = refreshEnvironment();
-		this.scope.refreshAll();
-		return keys;
+	public Set<String> refresh(Set<String> propertiesToRefresh, RefreshStrategy strategy) {
+        return strategy.refresh(this, propertiesToRefresh);
+    }
+
+	public synchronized Set<String> refreshSpecificEnvironment(Set<String> propertiesToRefresh){
+		//TODO: Implement this.
+		return propertiesToRefresh;
 	}
 
 	public synchronized Set<String> refreshEnvironment() {

spring-cloud-context/src/main/java/org/springframework/cloud/context/refresh/RefreshAllStrategy.java

@@ -0,0 +1,10 @@
+package org.springframework.cloud.context.refresh;
+
+import java.util.Set;
+
+public class RefreshAllStrategy implements RefreshStrategy {
+    @Override
+    public Set<String> refresh(ContextRefresher contextRefresher, Set<String> propertiesToRefresh) {
+        return contextRefresher.refreshEnvironment();
+    }
+}

spring-cloud-context/src/main/java/org/springframework/cloud/context/refresh/RefreshSpecificPropertiesStrategy.java

@@ -0,0 +1,10 @@
+package org.springframework.cloud.context.refresh;
+
+import java.util.Set;
+
+public class RefreshSpecificPropertiesStrategy implements RefreshStrategy {
+    @Override
+    public Set<String> refresh(ContextRefresher contextRefresher, Set<String> propertiesToRefresh) {
+        return contextRefresher.refreshSpecificEnvironment(propertiesToRefresh);
+    }
+}

spring-cloud-context/src/main/java/org/springframework/cloud/context/refresh/RefreshStrategy.java

@@ -0,0 +1,7 @@
+package org.springframework.cloud.context.refresh;
+
+import java.util.Set;
+
+public interface RefreshStrategy {
+    Set<String> refresh(ContextRefresher contextRefresher, Set<String> propertiesToRefresh);
+}

spring-cloud-context/src/main/java/org/springframework/cloud/endpoint/RefreshEndpoint.java

@@ -42,8 +42,11 @@ public RefreshEndpoint(ContextRefresher contextRefresher) {
 	}
 
 	@WriteOperation
-	public Collection<String> refresh() {
-		Set<String> keys = this.contextRefresher.refresh();
+    public Collection<String> refresh(Set<String> propertiesToRefresh) {
+        RefreshStrategy strategy = (propertiesToRefresh != null && !propertiesToRefresh.isEmpty())
+                ? new RefreshSpecificPropertiesStrategy()
+                : new RefreshAllStrategy();
+        Set<String> keys = this.contextRefresher.refresh(propertiesToRefresh, strategy);
 		LOG.info("Refreshed keys : " + keys);
 		return keys;
 	}