Applying RelaxedNames before filtering PropertySources

... to allow for OS_VAR to be bound to a @ConfigurationPropertes("os")
class with field "var".

Fixes gh-387, Fixes gh-391

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

@@ -253,17 +253,16 @@ public class PropertiesConfigurationFactory<T> implements FactoryBean<T>,
 		if (this.target != null) {
 			PropertyDescriptor[] descriptors = BeanUtils
 					.getPropertyDescriptors(this.target.getClass());
-			String[] prefixes = this.targetName != null ? new String[] {
+			String prefix = this.targetName != null ? this.targetName + "." : "";
-					this.targetName + ".", this.targetName + "_" } : new String[] { "" };
 			String[] suffixes = new String[] { ".*", "_*" };
 			for (PropertyDescriptor descriptor : descriptors) {
 				String name = descriptor.getName();
 				if (!name.equals("class")) {
-					for (String prefix : prefixes) {
+					for(String relaxedName : new RelaxedNames(prefix + name)) {
-						names.add(prefix + name);
+						names.add(relaxedName);
-						patterns.add(prefix + name);
+						patterns.add(relaxedName);
 						for (String suffix : suffixes) {
-							patterns.add(prefix + name + suffix);
+							patterns.add(relaxedName + suffix);
 						}
 					}
 				}

spring-boot/src/test/java/org/springframework/boot/context/properties/EnableConfigurationPropertiesTests.java

@@ -101,6 +101,16 @@ public class EnableConfigurationPropertiesTests {
 		assertEquals("bar", this.context.getBean(NestedProperties.class).nested.name);
 	}
 
+	@Test
+	public void testNestedOsEnvironmentVariableWithUnderscore() {
+		EnvironmentTestUtils.addEnvironment(this.context, "NAME:foo", "NESTED_NAME:bar");
+		this.context.register(NestedConfiguration.class);
+		this.context.refresh();
+		assertEquals(1, this.context.getBeanNamesForType(NestedProperties.class).length);
+		assertEquals("foo", this.context.getBean(NestedProperties.class).name);
+		assertEquals("bar", this.context.getBean(NestedProperties.class).nested.name);
+	}
+
 	@Test
 	public void testStrictPropertiesBinding() {
 		removeSystemProperties();
@@ -122,6 +132,16 @@ public class EnableConfigurationPropertiesTests {
 		assertEquals("foo", this.context.getBean(TestProperties.class).name);
 	}
 
+	@Test
+	public void testOsEnvironmentVariableEmbeddedBinding() {
+		EnvironmentTestUtils.addEnvironment(this.context, "SPRING_FOO_NAME:foo");
+		this.context.register(EmbeddedTestConfiguration.class);
+		this.context.refresh();
+		assertEquals(1,
+				this.context.getBeanNamesForType(EmbeddedTestProperties.class).length);
+		assertEquals("foo", this.context.getBean(TestProperties.class).name);
+	}
+
 	@Test
 	public void testIgnoreNestedPropertiesBinding() {
 		removeSystemProperties();