Fix binding to empty prefix when empty name present

Fixes gh-12381

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/Binder.java

@@ -46,6 +46,7 @@ import org.springframework.core.env.Environment;
 import org.springframework.format.support.DefaultFormattingConversionService;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * A container object which Binds objects from one or more
@@ -308,6 +309,9 @@ public class Binder {
 
 	private ConfigurationProperty findProperty(ConfigurationPropertyName name,
 			Context context) {
+		if (!StringUtils.hasText(name.toString())) {
+			return null;
+		}
 		return context.streamSources()
 				.map((source) -> source.getConfigurationProperty(name))
 				.filter(Objects::nonNull).findFirst().orElse(null);

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/BinderTests.java

@@ -20,7 +20,10 @@ import java.beans.PropertyEditorSupport;
 import java.time.LocalDate;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 import javax.validation.Validation;
 
@@ -40,6 +43,7 @@ import org.springframework.boot.context.properties.source.ConfigurationPropertyS
 import org.springframework.boot.context.properties.source.MockConfigurationPropertySource;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.convert.ConversionFailedException;
+import org.springframework.core.env.MapPropertySource;
 import org.springframework.core.env.PropertySource;
 import org.springframework.core.env.StandardEnvironment;
 import org.springframework.core.io.Resource;
@@ -301,6 +305,20 @@ public class BinderTests {
 		this.binder.bind("foo", target);
 	}
 
+	@Test
+	@SuppressWarnings("unchecked")
+	public void bindWithEmptyPrefixShouldIgnorePropertiesWithEmptyName() {
+		Map<String, Object> source = new HashMap<>();
+		source.put("value", "hello");
+		source.put("", "bar");
+		Iterable<ConfigurationPropertySource> propertySources = ConfigurationPropertySources.from(
+				new MapPropertySource("test", source));
+		this.sources.addAll((Set) propertySources);
+		Bindable<JavaBean> target = Bindable.of(JavaBean.class);
+		JavaBean result = this.binder.bind("", target).get();
+		assertThat(result.getValue()).isEqualTo("hello");
+	}
+
 	public static class JavaBean {
 
 		private String value;