Use LocaleDateTime codec for legacy Date-API

The current DateCodec for legacy `java.util.Date` was using
`java.time.Instant` which was itself incorrectly mapping to `TIMESTAMP`.
With the previous fix to `InstantCodec` the codec of `Date` had to be
changed so the more correct `LocalDateTimeCodec`.

Author: bzikarsky

src/main/java/io/r2dbc/postgresql/codec/DateCodec.java

@@ -24,18 +24,19 @@
 import io.r2dbc.postgresql.util.Assert;
 import reactor.util.annotation.Nullable;
 
-import java.time.Instant;
+import java.time.LocalDateTime;
+import java.time.ZoneId;
 import java.util.Date;
 
 final class DateCodec extends AbstractCodec<Date> {
 
-    private final InstantCodec delegate;
+    private final LocalDateTimeCodec delegate;
 
     DateCodec(ByteBufAllocator byteBufAllocator) {
         super(Date.class);
 
         Assert.requireNonNull(byteBufAllocator, "byteBufAllocator must not be null");
-        this.delegate = new InstantCodec(byteBufAllocator);
+        this.delegate = new LocalDateTimeCodec(byteBufAllocator);
     }
 
     @Override
@@ -55,14 +56,15 @@ boolean doCanDecode(PostgresqlObjectId type, Format format) {
     Date doDecode(ByteBuf buffer, PostgresqlObjectId dataType, @Nullable Format format, @Nullable Class<? extends Date> type) {
         Assert.requireNonNull(buffer, "byteBuf must not be null");
 
-        return Date.from(this.delegate.doDecode(buffer, dataType, format, Instant.class));
+        LocalDateTime intermediary = this.delegate.doDecode(buffer, dataType, format, LocalDateTime.class);
+        return Date.from(intermediary.atZone(ZoneId.systemDefault()).toInstant());
     }
 
     @Override
     Parameter doEncode(Date value) {
         Assert.requireNonNull(value, "value must not be null");
 
-        return this.delegate.doEncode(value.toInstant());
+        return this.delegate.doEncode(value.toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime());
     }
 
 }

src/main/java/io/r2dbc/postgresql/codec/LocalDateTimeCodec.java

@@ -25,9 +25,7 @@
 import io.r2dbc.postgresql.util.ByteBufUtils;
 import reactor.util.annotation.Nullable;
 
-import java.time.Instant;
-import java.time.LocalDateTime;
-import java.time.ZoneOffset;
+import java.time.*;
 
 import static io.r2dbc.postgresql.message.Format.FORMAT_TEXT;
 import static io.r2dbc.postgresql.type.PostgresqlObjectId.TIMESTAMP;
@@ -51,6 +49,10 @@ LocalDateTime doDecode(ByteBuf buffer, PostgresqlObjectId dataType, @Nullable Fo
         Assert.requireNonNull(buffer, "byteBuf must not be null");
 
         return decodeTemporal(buffer, dataType, format, LocalDateTime.class, temporal -> {
+            if (temporal instanceof LocalDate) {
+                return ((LocalDate) temporal).atStartOfDay(ZoneId.systemDefault()).toLocalDateTime();
+            }
+
             return Instant.from(temporal).atOffset(ZoneOffset.UTC).toLocalDateTime();
         });
     }

src/test/java/io/r2dbc/postgresql/codec/DateCodecTest.java

@@ -49,9 +49,10 @@ void constructorNoByteBufAllocator() {
 
     @Test
     void decode() {
-        Date date = Date.from(Instant.parse("2018-11-04T15:37:31.177Z"));
+        Instant testInstant = LocalDateTime.parse("2010-02-01T10:08:04.412").atZone(ZoneId.systemDefault()).toInstant();
+        Date date = Date.from(testInstant);
 
-        assertThat(new DateCodec(TEST).decode(encode(TEST, "2018-11-04 15:37:31.177"), dataType, FORMAT_TEXT, Date.class))
+        assertThat(new DateCodec(TEST).decode(encode(TEST, "2010-02-01 10:08:04.412"), dataType, FORMAT_TEXT, Date.class))
             .isEqualTo(date);
     }
 
@@ -91,12 +92,13 @@ void doCanDecodeNoType() {
 
     @Test
     void doEncode() {
-        Date date = new Date();
+        Instant testInstant = LocalDateTime.parse("2010-02-01T10:08:04.412").atZone(ZoneId.systemDefault()).toInstant();
+        Date date = Date.from(testInstant);
 
         assertThat(new DateCodec(TEST).doEncode(date))
             .hasFormat(FORMAT_TEXT)
             .hasType(TIMESTAMP.getObjectId())
-            .hasValue(encode(TEST, date.toInstant().toString()));
+            .hasValue(encode(TEST, "2010-02-01T10:08:04.412"));
     }
 
     @Test