#786 Convert Java offset names to Firebird offset names

src/docs/asciidoc/release_notes.adoc

@@ -927,6 +927,7 @@ We do not plan to remove this API at this time, but we recommend that you switch
 * Fixed: Use of offset timezone names (e.g. `+05:00`) for `sessionTimeZone` would result in a warning being logged, and an incorrect conversion applied (in UTC instead of the offset) when using the legacy time types (https://github.com/FirebirdSQL/jaybird/issues/786[#786])
 +
 This change was also backported to Jaybird 5.0.4.
+* Improvement: `sessionTimeZone` now also accepts the Java offset names (`GMT[{plus}-]HH:MM`), which will be automatically converted to the Firebird compatible name (`[{plus}-]HH:MM`).
 
 [#potentially-breaking-changes]
 === Potentially breaking changes

src/main/org/firebirdsql/gds/ng/FbConnectionProperties.java

@@ -30,8 +30,6 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.TimeZone;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
 
 /**
  * Mutable implementation of {@link IConnectionProperties}
@@ -43,8 +41,6 @@
 public final class FbConnectionProperties extends AbstractAttachProperties<IConnectionProperties>
         implements IConnectionProperties, Serializable {
 
-    private static final Pattern GMT_WITH_OFFSET = Pattern.compile("^GMT([+-]\\d{2}:\\d{2})$");
-
     @SuppressWarnings("java:S1948")
     private FbImmutableConnectionProperties immutableConnectionPropertiesCache;
 
@@ -98,14 +94,7 @@ protected Object resolveStoredDefaultValue(ConnectionProperty property) {
     }
 
     private static String defaultTimeZone() {
-        String timeZone = TimeZone.getDefault().getID();
-        if (timeZone.startsWith("GMT") && timeZone.length() > 3) {
-            Matcher matcher = GMT_WITH_OFFSET.matcher(timeZone);
-            if (matcher.matches()) {
-                return matcher.group(1);
-            }
-        }
-        return timeZone;
+        return TimeZone.getDefault().getID();
     }
 
     @Override

src/main/org/firebirdsql/jaybird/props/DatabaseConnectionProperties.java

@@ -27,6 +27,8 @@
 import org.firebirdsql.jdbc.FirebirdCallableStatement;
 
 import java.sql.DatabaseMetaData;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 /**
  * Properties for database connections.
@@ -190,11 +192,32 @@ default String getSessionTimeZone() {
      *
      * @param sessionTimeZone
      *         Firebird 4+ session time zone name (we strongly suggest to use Java compatible names only),
-     *         use {@code "server"} to use server default time zone (note: conversion will use JVM default time zone)
+     *         use {@code "server"} to use server default time zone (note: conversion will use JVM default time zone).
+     *         For offset-based names, the value will be normalized to the Firebird name (e.g. GMT+05:00 is stored as
+     *         +05:00).
      * @since 4.0
      */
     default void setSessionTimeZone(String sessionTimeZone) {
-        setProperty(PropertyNames.sessionTimeZone, sessionTimeZone);
+        setProperty(PropertyNames.sessionTimeZone, normalizeTimeZone(sessionTimeZone));
+    }
+
+    /**
+     * Normalizes timezone name, specifically converts Java's {@code GMT[+-]HH:MM} to Firebird's {@code [+-]HH:MM}.
+     *
+     * @param timeZone timezone name
+     * @return original or modified timezone name
+     */
+    private static String normalizeTimeZone(String timeZone) {
+        @SuppressWarnings("java:S1118")
+        final class Holder {
+            static final Pattern GMT_WITH_OFFSET = Pattern.compile("^GMT([+-]\\d{2}:\\d{2})$");
+        }
+        if (timeZone == null) return null;
+        Matcher matcher = Holder.GMT_WITH_OFFSET.matcher(timeZone);
+        if (matcher.matches()) {
+            return matcher.group(1);
+        }
+        return timeZone;
     }
 
     /**

src/test/org/firebirdsql/gds/ng/FbConnectionPropertiesTest.java

@@ -243,7 +243,7 @@ void testAsImmutable() {
     }
 
     @Test
-    void testSessionTimeZoneSpecialGmtOffsetHandling() {
+    void testSessionTimeZoneDefaultSpecialGmtOffsetHandling() {
         final TimeZone before = TimeZone.getDefault();
         try {
             TimeZone.setDefault(TimeZone.getTimeZone("GMT-08:00"));
@@ -254,4 +254,11 @@ void testSessionTimeZoneSpecialGmtOffsetHandling() {
             TimeZone.setDefault(before);
         }
     }
+
+    @Test
+    void testSessionTimeZoneNormalizationOfOffsets() {
+        info.setSessionTimeZone("GMT+05:00");
+        assertEquals("+05:00", info.getSessionTimeZone());
+    }
+
 }