Issuer should not support path component

Closes gh-1435

oauth2-authorization-server/src/test/java/org/springframework/security/oauth2/server/authorization/config/annotation/web/configurers/OidcProviderConfigurationTests.java

@@ -161,6 +161,13 @@ public class OidcProviderConfigurationTests {
 		);
 	}
 
+	@Test
+	public void loadContextWhenIssuerWithPathThenThrowException() {
+		assertThatThrownBy(
+				() -> this.spring.register(AuthorizationServerConfigurationWithIssuerPath.class).autowire()
+		);
+	}
+
 	@Test
 	public void loadContextWhenIssuerWithQueryThenThrowException() {
 		assertThatThrownBy(
@@ -182,6 +189,13 @@ public class OidcProviderConfigurationTests {
 		);
 	}
 
+	@Test
+	public void loadContextWhenIssuerWithEmptyPathThenThrowException() {
+		assertThatThrownBy(
+				() -> this.spring.register(AuthorizationServerConfigurationWithIssuerEmptyPath.class).autowire()
+		);
+	}
+
 	@Test
 	public void loadContextWhenIssuerWithEmptyQueryThenThrowException() {
 		assertThatThrownBy(
@@ -299,6 +313,15 @@ public class OidcProviderConfigurationTests {
 		}
 	}
 
+	@EnableWebSecurity
+	static class AuthorizationServerConfigurationWithIssuerPath extends AuthorizationServerConfiguration {
+
+		@Bean
+		AuthorizationServerSettings authorizationServerSettings() {
+			return AuthorizationServerSettings.builder().issuer(ISSUER_URL + "/issuer1").build();
+		}
+	}
+
 	@EnableWebSecurity
 	static class AuthorizationServerConfigurationWithIssuerQuery extends AuthorizationServerConfiguration {
 
@@ -326,6 +349,15 @@ public class OidcProviderConfigurationTests {
 		}
 	}
 
+	@EnableWebSecurity
+	static class AuthorizationServerConfigurationWithIssuerEmptyPath extends AuthorizationServerConfiguration {
+
+		@Bean
+		AuthorizationServerSettings authorizationServerSettings() {
+			return AuthorizationServerSettings.builder().issuer(ISSUER_URL + "/").build();
+		}
+	}
+
 	@EnableWebSecurity
 	static class AuthorizationServerConfigurationWithIssuerEmptyQuery extends AuthorizationServerConfiguration {