Validate Spring Session database initializer configuration

This commit adds Spring Session JDBC configuration validation that
disables database initializer in case custom table name is configured
with default schema.

See gh-6649

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/session/SessionProperties.java

@@ -107,6 +107,8 @@ public class SessionProperties {
 		private static final String DEFAULT_SCHEMA_LOCATION = "classpath:org/springframework/"
 				+ "session/jdbc/schema-@@platform@@.sql";
 
+		private static final String DEFAULT_TABLE_NAME = "SPRING_SESSION";
+
 		/**
 		 * Path to the SQL file to use to initialize the database schema.
 		 */
@@ -115,7 +117,7 @@ public class SessionProperties {
 		/**
 		 * Name of database table used to store sessions.
 		 */
-		private String tableName = "SPRING_SESSION";
+		private String tableName = DEFAULT_TABLE_NAME;
 
 		private final Initializer initializer = new Initializer();
 
@@ -139,7 +141,7 @@ public class SessionProperties {
 			return this.initializer;
 		}
 
-		public static class Initializer {
+		public class Initializer {
 
 			/**
 			 * Create the required session tables on startup if necessary.
@@ -147,7 +149,11 @@ public class SessionProperties {
 			private boolean enabled = true;
 
 			public boolean isEnabled() {
-				return this.enabled;
+				boolean isDefaultTableName = DEFAULT_TABLE_NAME.equals(
+						Jdbc.this.getTableName());
+				boolean isDefaultSchema = DEFAULT_SCHEMA_LOCATION.equals(
+						Jdbc.this.getSchema());
+				return this.enabled && (isDefaultTableName || !isDefaultSchema);
 			}
 
 			public void setEnabled(boolean enabled) {

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/session/SessionAutoConfigurationJdbcTests.java

@@ -54,6 +54,8 @@ public class SessionAutoConfigurationJdbcTests
 				JdbcOperationsSessionRepository.class);
 		assertThat(new DirectFieldAccessor(repository).getPropertyValue("tableName"))
 				.isEqualTo("SPRING_SESSION");
+		assertThat(this.context.getBean(SessionProperties.class)
+				.getJdbc().getInitializer().isEnabled()).isTrue();
 		assertThat(this.context.getBean(JdbcOperations.class)
 				.queryForList("select * from SPRING_SESSION")).isEmpty();
 	}
@@ -68,6 +70,8 @@ public class SessionAutoConfigurationJdbcTests
 				JdbcOperationsSessionRepository.class);
 		assertThat(new DirectFieldAccessor(repository).getPropertyValue("tableName"))
 				.isEqualTo("SPRING_SESSION");
+		assertThat(this.context.getBean(SessionProperties.class)
+				.getJdbc().getInitializer().isEnabled()).isFalse();
 		this.thrown.expect(BadSqlGrammarException.class);
 		assertThat(this.context.getBean(JdbcOperations.class)
 				.queryForList("select * from SPRING_SESSION")).isEmpty();
@@ -84,8 +88,27 @@ public class SessionAutoConfigurationJdbcTests
 				JdbcOperationsSessionRepository.class);
 		assertThat(new DirectFieldAccessor(repository).getPropertyValue("tableName"))
 				.isEqualTo("FOO_BAR");
+		assertThat(this.context.getBean(SessionProperties.class)
+				.getJdbc().getInitializer().isEnabled()).isTrue();
 		assertThat(this.context.getBean(JdbcOperations.class)
 				.queryForList("select * from FOO_BAR")).isEmpty();
 	}
 
+	@Test
+	public void customTableNameWithDefaultSchemaDisablesInitializer() {
+		load(Arrays.asList(EmbeddedDataSourceConfiguration.class,
+				DataSourceTransactionManagerAutoConfiguration.class),
+				"spring.session.store-type=jdbc",
+				"spring.session.jdbc.table-name=FOO_BAR");
+		JdbcOperationsSessionRepository repository = validateSessionRepository(
+				JdbcOperationsSessionRepository.class);
+		assertThat(new DirectFieldAccessor(repository).getPropertyValue("tableName"))
+				.isEqualTo("FOO_BAR");
+		assertThat(this.context.getBean(SessionProperties.class)
+				.getJdbc().getInitializer().isEnabled()).isFalse();
+		this.thrown.expect(BadSqlGrammarException.class);
+		assertThat(this.context.getBean(JdbcOperations.class)
+				.queryForList("select * from SPRING_SESSION")).isEmpty();
+	}
+
 }