diff --git a/core/src/main/java/org/springframework/security/core/userdetails/MapReactiveUserDetailsService.java b/core/src/main/java/org/springframework/security/core/userdetails/MapReactiveUserDetailsService.java
index a0cb3e0373..96dc152a91 100644
--- a/core/src/main/java/org/springframework/security/core/userdetails/MapReactiveUserDetailsService.java
+++ b/core/src/main/java/org/springframework/security/core/userdetails/MapReactiveUserDetailsService.java
@@ -43,7 +43,7 @@ public class MapReactiveUserDetailsService implements ReactiveUserDetailsService
 
 	public MapReactiveUserDetailsService(Collection<UserDetails> users) {
 		Assert.notEmpty(users, "users cannot be null or empty");
-		this.users = users.stream().collect(Collectors.toConcurrentMap( u -> getKey(u.getName()), Function.identity()));
+		this.users = users.stream().collect(Collectors.toConcurrentMap( u -> getKey(u.getUsername()), Function.identity()));
 	}
 
 	@Override
diff --git a/core/src/main/java/org/springframework/security/core/userdetails/UserDetails.java b/core/src/main/java/org/springframework/security/core/userdetails/UserDetails.java
index 9f02589ad5..a396f853c7 100644
--- a/core/src/main/java/org/springframework/security/core/userdetails/UserDetails.java
+++ b/core/src/main/java/org/springframework/security/core/userdetails/UserDetails.java
@@ -18,7 +18,6 @@ package org.springframework.security.core.userdetails;
 
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.GrantedAuthority;
-import org.springframework.security.core.AuthenticatedPrincipal;
 
 import java.io.Serializable;
 import java.util.Collection;
@@ -42,7 +41,7 @@ import java.util.Collection;
  *
  * @author Ben Alex
  */
-public interface UserDetails extends AuthenticatedPrincipal, Serializable {
+public interface UserDetails extends Serializable {
 	// ~ Methods
 	// ========================================================================================================
 
@@ -100,14 +99,4 @@ public interface UserDetails extends AuthenticatedPrincipal, Serializable {
 	 * @return <code>true</code> if the user is enabled, <code>false</code> otherwise
 	 */
 	boolean isEnabled();
-
-	/**
-	 * Returns the name of the user. Cannot return <code>null</code>.
-	 * The default implementation of this method returns {@link #getUsername()}.
-	 *
-	 * @return the name of the user (never <code>null</code>)
-	 */
-	default String getName() {
-		return getUsername();
-	}
 }
diff --git a/core/src/test/java/org/springframework/security/core/userdetails/UserDetailsTest.java b/core/src/test/java/org/springframework/security/core/userdetails/UserDetailsTest.java
deleted file mode 100644
index 14f6ed2348..0000000000
--- a/core/src/test/java/org/springframework/security/core/userdetails/UserDetailsTest.java
+++ /dev/null
@@ -1,81 +0,0 @@
-/*
- * Copyright 2002-2017 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.security.core.userdetails;
-
-import org.junit.Test;
-import org.springframework.security.core.GrantedAuthority;
-import org.springframework.security.core.authority.AuthorityUtils;
-
-import java.util.Collection;
-
-import static org.assertj.core.api.Assertions.assertThat;
-
-/**
- * Tests {@link UserDetails}
- *
- * @author Joe Grandja
- */
-public class UserDetailsTest {
-
-	@Test
-	public void getNameWhenCalledThenDefaultToGetUsername() {
-		UserDetails userDetails = new MockUserDetails("joeg");
-		assertThat(userDetails.getName()).isEqualTo(userDetails.getUsername());
-	}
-
-	private class MockUserDetails implements UserDetails {
-		private final String username;
-
-		private MockUserDetails(String username) {
-			this.username = username;
-		}
-
-		@Override
-		public Collection<? extends GrantedAuthority> getAuthorities() {
-			return AuthorityUtils.NO_AUTHORITIES;
-		}
-
-		@Override
-		public String getPassword() {
-			return null;
-		}
-
-		@Override
-		public String getUsername() {
-			return this.username;
-		}
-
-		@Override
-		public boolean isAccountNonExpired() {
-			return true;
-		}
-
-		@Override
-		public boolean isAccountNonLocked() {
-			return true;
-		}
-
-		@Override
-		public boolean isCredentialsNonExpired() {
-			return true;
-		}
-
-		@Override
-		public boolean isEnabled() {
-			return true;
-		}
-	}
-}