NPE in VaultEnvironmentRepository.findOne
When reading a value from vault it is possible there is no value for a given key so we should check for null before trying to convert the key/value to YAML.

```
java.lang.NullPointerException: null
    at org.springframework.cloud.config.server.environment.VaultEnvironmentRepository.findOne(VaultEnvironmentRepository.java:94) ~[spring-cloud-config-server-1.2.0.BUILD-SNAPSHOT.jar:1.2.0.BUILD-SNAPSHOT]
    at org.springframework.cloud.config.server.environment.EnvironmentEncryptorEnvironmentRepository.findOne(EnvironmentEncryptorEnvironmentRepository.java:53) ~[spring-cloud-config-server-1.2.0.BUILD-SNAPSHOT.jar:1.2.0.BUILD-SNAPSHOT]
    at org.springframework.cloud.config.server.environment.EnvironmentController.labelled(EnvironmentController.java:112) ~[spring-cloud-config-server-1.2.0.BUILD-SNAPSHOT.jar:1.2.0.BUILD-SNAPSHOT]
    at org.springframework.cloud.config.server.environment.EnvironmentController.defaultLabel(EnvironmentController.java:101) ~[spring-cloud-config-server-1.2.0.BUILD-SNAPSHOT.jar:1.2.0.BUILD-SNAPSHOT]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.7.0_79]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[na:1.7.0_79]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_79]
    at java.lang.reflect.Method.invoke(Method.java:606) ~[na:1.7.0_79]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:832) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:743) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:961) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:858) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843) ~[spring-webmvc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.springframework.boot.actuate.autoconfigure.EndpointWebMvcAutoConfiguration$ApplicationContextHeaderFilter.doFilterInternal(EndpointWebMvcAutoConfiguration.java:281) ~[spring-boot-actuator-1.3.6.RELEASE.jar:1.3.6.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:115) ~[spring-boot-actuator-1.3.6.RELEASE.jar:1.3.6.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:103) ~[spring-boot-actuator-1.3.6.RELEASE.jar:1.3.6.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.7.RELEASE.jar:4.2.7.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212) ~[tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) [tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) [tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141) [tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) [tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:528) [tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1099) [tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:670) [tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520) [tomcat-embed-core-8.0.36.jar:8.0.36]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476) [tomcat-embed-core-8.0.36.jar:8.0.36]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_79]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_79]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.0.36.jar:8.0.36]
    at java.lang.Thread.run(Thread.java:745) [na:1.7.0_79]
```

diff --git a/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/config/EnvironmentRepositoryConfiguration.java b/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/config/EnvironmentRepositoryConfiguration.java
index 79a34643..3638f0b7 100644
--- a/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/config/EnvironmentRepositoryConfiguration.java
+++ b/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/config/EnvironmentRepositoryConfiguration.java
@@ -32,6 +32,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Profile;
 import org.springframework.core.env.ConfigurableEnvironment;
+import org.springframework.web.client.RestTemplate;
 
 /**
  * @author Dave Syer
@@ -106,7 +107,7 @@ public class EnvironmentRepositoryConfiguration {
 	protected static class VaultConfiguration {
 		@Bean
 		public EnvironmentRepository environmentRepository(HttpServletRequest request, EnvironmentWatch watch) {
-			return new VaultEnvironmentRepository(request, watch);
+			return new VaultEnvironmentRepository(request, watch, new RestTemplate());
 		}
 	}
 
diff --git a/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/VaultEnvironmentRepository.java b/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/VaultEnvironmentRepository.java
index 57b4243f..e7e5290a 100644
--- a/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/VaultEnvironmentRepository.java
+++ b/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/VaultEnvironmentRepository.java
@@ -61,16 +61,17 @@ public class VaultEnvironmentRepository implements EnvironmentRepository {
 	@NotEmpty
 	private String profileSeparator = ",";
 
-	private RestTemplate rest = new RestTemplate();
+	private RestTemplate rest;
 
 	//TODO: move to watchState:String on findOne?
 	private HttpServletRequest request;
 
 	private EnvironmentWatch watch;
 
-	public VaultEnvironmentRepository(HttpServletRequest request, EnvironmentWatch watch) {
+	public VaultEnvironmentRepository(HttpServletRequest request, EnvironmentWatch watch, RestTemplate rest) {
 		this.request = request;
 		this.watch = watch;
+		this.rest = rest;
 	}
 
 	@Override
@@ -89,13 +90,15 @@ public class VaultEnvironmentRepository implements EnvironmentRepository {
 		for (String key : keys) {
 			// read raw 'data' key from vault
 			String data = read(key);
-			// data is in json format of which, yaml is a superset, so parse
-			final YamlPropertiesFactoryBean yaml = new YamlPropertiesFactoryBean();
-			yaml.setResources(new ByteArrayResource(data.getBytes()));
-			Properties properties = yaml.getObject();
-
-			if (!properties.isEmpty()) {
-				environment.add(new PropertySource("vault:"+key, properties));
+			if (data != null) {
+				// data is in json format of which, yaml is a superset, so parse
+				final YamlPropertiesFactoryBean yaml = new YamlPropertiesFactoryBean();
+				yaml.setResources(new ByteArrayResource(data.getBytes()));
+				Properties properties = yaml.getObject();
+
+				if (!properties.isEmpty()) {
+					environment.add(new PropertySource("vault:" + key, properties));
+				}
 			}
 		}
 
diff --git a/spring-cloud-config-server/src/test/java/org/springframework/cloud/config/server/environment/VaultEnvironmentRepositoryTests.java b/spring-cloud-config-server/src/test/java/org/springframework/cloud/config/server/environment/VaultEnvironmentRepositoryTests.java
index d213f1b7..a3962d85 100644
--- a/spring-cloud-config-server/src/test/java/org/springframework/cloud/config/server/environment/VaultEnvironmentRepositoryTests.java
+++ b/spring-cloud-config-server/src/test/java/org/springframework/cloud/config/server/environment/VaultEnvironmentRepositoryTests.java
@@ -1,14 +1,74 @@
 package org.springframework.cloud.config.server.environment;
 
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.junit.Before;
 import org.junit.Test;
+import org.mockito.Mockito;
+import org.springframework.cloud.config.environment.Environment;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.web.client.RestTemplate;
 
 /**
  * @author Spencer Gibb
+ * @author Ryan Baxter
  */
 public class VaultEnvironmentRepositoryTests {
 
+
+	@Before
+	public void init() {}
+
 	@Test
-	public void testFindOne() {
-		//TODO: implement testFindOne
+	public void testFindOne() throws IOException {
+		MockHttpServletRequest configRequest = new MockHttpServletRequest();
+		configRequest.addHeader("X-CONFIG-TOKEN", "mytoken");
+		RestTemplate rest = Mockito.mock(RestTemplate.class);
+		ResponseEntity<VaultEnvironmentRepository.VaultResponse> myAppResp = Mockito.mock(ResponseEntity.class);
+		Mockito.when(myAppResp.getStatusCode()).thenReturn(HttpStatus.OK);
+		VaultEnvironmentRepository.VaultResponse myAppVaultResp = Mockito.mock(VaultEnvironmentRepository.VaultResponse.class);
+		Mockito.when(myAppVaultResp.getData()).thenReturn("{\\"foo\\":\\"bar\\"}");
+		Mockito.when(myAppResp.getBody()).thenReturn(myAppVaultResp);
+		Mockito.when(rest.exchange(Mockito.eq("http://127.0.0.1:8200/v1/{backend}/{key}"),
+				Mockito.eq(HttpMethod.GET), Mockito.any(HttpEntity.class), Mockito.eq(VaultEnvironmentRepository.VaultResponse.class),
+				Mockito.eq("secret"), Mockito.eq("myapp"))).thenReturn(myAppResp);
+		ResponseEntity<VaultEnvironmentRepository.VaultResponse> appResp = Mockito.mock(ResponseEntity.class);
+		Mockito.when(appResp.getStatusCode()).thenReturn(HttpStatus.OK);
+		VaultEnvironmentRepository.VaultResponse appVaultResp = Mockito.mock(VaultEnvironmentRepository.VaultResponse.class);
+		Mockito.when(appVaultResp.getData()).thenReturn(null);
+		Mockito.when(appResp.getBody()).thenReturn(appVaultResp);
+		Mockito.when(rest.exchange(Mockito.eq("http://127.0.0.1:8200/v1/{backend}/{key}"),
+				Mockito.eq(HttpMethod.GET), Mockito.any(HttpEntity.class), Mockito.eq(VaultEnvironmentRepository.VaultResponse.class),
+				Mockito.eq("secret"), Mockito.eq("application"))).thenReturn(appResp);
+		VaultEnvironmentRepository repo = new VaultEnvironmentRepository(configRequest, new EnvironmentWatch.Default(), rest);
+		Environment e = repo.findOne("myapp", null, null);
+		assertEquals("myapp", e.getName());
+		Map<String,String> result = new HashMap<String,String>();
+		result.put("foo", "bar");
+		assertEquals(result, e.getPropertySources().get(0).getSource());
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void missingConfigToken() throws IOException {
+		MockHttpServletRequest configRequest = new MockHttpServletRequest();
+		RestTemplate rest = Mockito.mock(RestTemplate.class);
+		ResponseEntity<VaultEnvironmentRepository.VaultResponse> myAppResp = Mockito.mock(ResponseEntity.class);
+		Mockito.when(myAppResp.getStatusCode()).thenReturn(HttpStatus.OK);
+		VaultEnvironmentRepository.VaultResponse myAppVaultResp = Mockito.mock(VaultEnvironmentRepository.VaultResponse.class);
+		Mockito.when(myAppVaultResp.getData()).thenReturn("{\\"foo\\":\\"bar\\"}");
+		Mockito.when(myAppResp.getBody()).thenReturn(myAppVaultResp);
+		Mockito.when(rest.exchange(Mockito.eq("http://127.0.0.1:8200/v1/{backend}/{key}"),
+				Mockito.eq(HttpMethod.GET), Mockito.any(HttpEntity.class), Mockito.eq(VaultEnvironmentRepository.VaultResponse.class),
+				Mockito.eq("secret"), Mockito.eq("myapp"))).thenReturn(myAppResp);
+		VaultEnvironmentRepository repo = new VaultEnvironmentRepository(configRequest, new EnvironmentWatch.Default(), rest);
+		repo.findOne("myapp", null, null);
 	}
 }
['spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/config/EnvironmentRepositoryConfiguration.java', 'spring-cloud-config-server/src/test/java/org/springframework/cloud/config/server/environment/VaultEnvironmentRepositoryTests.java', 'spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/VaultEnvironmentRepository.java']