Additional standard conversions (#382)

Author: wog48

jpa/odata-jpa-processor-cb/src/main/java/com/sap/olingo/jpa/processor/cb/impl/TypeConverter.java

@@ -46,6 +46,9 @@ static Object convert(final Object source, final Class<?> target) { // NOSONAR
       }
       if (target == Duration.class) {
         return convertDuration(source);
+      }
+      if (target == Timestamp.class) {
+        return convertTimestamp(source);
       } else {
         LOGGER.debug("No converter found to convert " + source.getClass().getSimpleName() + " to " + target
             .getSimpleName());
@@ -61,7 +64,7 @@ private static Character convertToCharacter(final String source) {
       LOGGER.debug("Implicit conversion to Character from String only supported if String not longer than 1");
       throw new IllegalArgumentException("String to long");
     }
-    if (source.length() == 0)
+    if (source.isEmpty())
       return ' ';
     return source.charAt(0);
   }
@@ -138,6 +141,17 @@ private static OffsetDateTime convertTemporalToOffsetDateTime(final Object sourc
     return OffsetDateTime.parse((String) source);
   }
 
+  private static Timestamp convertTimestamp(Object source) {
+    if (source instanceof LocalDateTime ldt)
+      return Timestamp.valueOf(ldt);
+    if (source instanceof LocalDate ld)
+      return Timestamp.valueOf(LocalDateTime.of(ld, LocalTime.of(0, 0)));
+    if (source instanceof String s)
+      return Timestamp.valueOf(s);
+    LOGGER.debug("No converter found to convert " + source.getClass().getSimpleName() + " to Timestamp");
+    throw new IllegalArgumentException(createCastException(source, Timestamp.class));
+  }
+
   public static Class<?> boxed(final Class<?> javaType) {
     if (javaType == int.class) return Integer.class;
     if (javaType == long.class) return Long.class;

jpa/odata-jpa-processor-cb/src/test/java/com/sap/olingo/jpa/processor/cb/impl/TypeConverterTest.java

@@ -152,7 +152,12 @@ static Stream<Arguments> temporalConversion() {
         arguments(LocalDateTime.parse("2007-12-03T10:15:30.05"), "2007-12-03T10:15:30.05", LocalDateTime.class),
         arguments(OffsetTime.parse("10:15:30+01:00"), "10:15:30+01:00", OffsetTime.class),
         arguments(OffsetDateTime.parse("2007-12-03T10:15:30+01:00"), "2007-12-03T10:15:30+01:00",
-            OffsetDateTime.class));
+            OffsetDateTime.class),
+        arguments(Timestamp.valueOf("2007-12-03 10:15:30.05"), LocalDateTime.parse("2007-12-03T10:15:30.05"),
+            Timestamp.class),
+        arguments(Timestamp.valueOf("2007-12-03 00:00:00"), LocalDate.parse("2007-12-03"),
+            Timestamp.class),
+        arguments(Timestamp.valueOf("2007-12-03 10:15:30.05"), "2007-12-03 10:15:30.05", Timestamp.class));
   }
 
   static Stream<Arguments> durationConversion() {