Polish duplicate key exception error code support for SAP HANA database for R2DBC

See gh-31554

spring-r2dbc/src/main/java/org/springframework/r2dbc/connection/ConnectionFactoryUtils.java

@@ -72,12 +72,12 @@ public abstract class ConnectionFactoryUtils {
 	public static final int CONNECTION_SYNCHRONIZATION_ORDER = 1000;
 
 	private static final Set<Integer> DUPLICATE_KEY_ERROR_CODES = Set.of(
-			1,	   // Oracle
+			1,     // Oracle
-			301,   // Sap Hana
+			301,   // SAP HANA
 			1062,  // MySQL/MariaDB
 			2601,  // MS SQL Server
 			2627   // MS SQL Server
-	);
+		);
 
 
 	/**
@@ -257,11 +257,13 @@ public abstract class ConnectionFactoryUtils {
 	}
 
 	/**
-	 * Check whether the given SQL state (and the associated error code in case
+	 * Check whether the given SQL state and the associated error code (in case
-	 * of a generic SQL state value) indicate a duplicate key exception. See
+	 * of a generic SQL state value) indicate a duplicate key exception:
-	 * {@code org.springframework.jdbc.support.SQLStateSQLExceptionTranslator#indicatesDuplicateKey}.
+	 * either SQL state 23505 as a specific indication, or the generic SQL state
+	 * 23000 with a well-known vendor code.
 	 * @param sqlState the SQL state value
-	 * @param errorCode the error code value
+	 * @param errorCode the error code
+	 * @see org.springframework.jdbc.support.SQLStateSQLExceptionTranslator#indicatesDuplicateKey
 	 */
 	static boolean indicatesDuplicateKey(@Nullable String sqlState, int errorCode) {
 		return ("23505".equals(sqlState) ||

spring-r2dbc/src/test/java/org/springframework/r2dbc/connection/ConnectionFactoryUtilsUnitTests.java

@@ -102,7 +102,7 @@ class ConnectionFactoryUtilsUnitTests {
 
 		exception = ConnectionFactoryUtils.convertR2dbcException("", "",
 				new R2dbcDataIntegrityViolationException("reason", "23000", 301));
-		assertThat(exception).isExactlyInstanceOf(DuplicateKeyException.class);
+		assertThat(exception).as("SAP HANA").isExactlyInstanceOf(DuplicateKeyException.class);
 
 		exception = ConnectionFactoryUtils.convertR2dbcException("", "",
 				new R2dbcDataIntegrityViolationException("reason", "23000", 1062));