Add suffix dot on prefix only if necessary

Closes spring-projectsgh-3787

Author: snicoll

spring-boot/src/main/java/org/springframework/boot/bind/RelaxedDataBinder.java

@@ -45,6 +45,7 @@
  *
  * @author Dave Syer
  * @author Phillip Webb
+ * @author Stephane Nicoll
  * @see RelaxedNames
  */
 public class RelaxedDataBinder extends DataBinder {
@@ -73,7 +74,14 @@ public RelaxedDataBinder(Object target) {
 	public RelaxedDataBinder(Object target, String namePrefix) {
 		super(wrapTarget(target), (StringUtils.hasLength(namePrefix) ? namePrefix
 				: DEFAULT_OBJECT_NAME));
-		this.namePrefix = (StringUtils.hasLength(namePrefix) ? namePrefix + "." : null);
+		this.namePrefix = cleanNamePrefix(namePrefix);
+	}
+
+	private static String cleanNamePrefix(String namePrefix) {
+		if (!StringUtils.hasLength(namePrefix)) {
+			return null;
+		}
+		return (namePrefix.endsWith(".") ? namePrefix : namePrefix + ".");
 	}
 
 	/**

spring-boot/src/test/java/org/springframework/boot/bind/RelaxedDataBinderTests.java

@@ -95,6 +95,13 @@ public void testBindStringWithPrefix() throws Exception {
 		assertEquals("bar", target.getFoo());
 	}
 
+	@Test
+	public void testBindStringWithPrefixDotSuffix() throws Exception {
+		VanillaTarget target = new VanillaTarget();
+		bind(target, "some.test.foo: bar", "some.test.");
+		assertEquals("bar", target.getFoo());
+	}
+
 	@Test
 	public void testBindFromEnvironmentStyleWithPrefix() throws Exception {
 		VanillaTarget target = new VanillaTarget();