Implementing a workaround for an invalid format in the defaultValue.

src/main/java/com/kintone/client/model/app/field/DateTimeFieldProperty.java

@@ -3,6 +3,8 @@
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.kintone.client.model.record.FieldType;
 import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
 import lombok.Data;
 
 /**
@@ -13,6 +15,8 @@
 @JsonIgnoreProperties(value = "type", allowGetters = true)
 public class DateTimeFieldProperty implements FieldProperty {
 
+    private final DateTimeFormatter DEFAULT_VALUE_FORMATTER = DateTimeFormatter.ISO_ZONED_DATE_TIME;
+
     /** The field code of the field. */
     private String code;
 
@@ -55,4 +59,23 @@ public class DateTimeFieldProperty implements FieldProperty {
     public FieldType getType() {
         return FieldType.DATETIME;
     }
+
+    // Kintone API returns defaultValue in the format of `yyyy-MM-dd'T'HH:mm`.
+    // This value is lack of compatibility with the ISO-8601 format, so DateTimeParseException occurs like following.
+    // java.time.format.DateTimeParseException: Text '2019-03-27T10:15' could not be parsed: Unable to obtain ZonedDateTime from TemporalAccessor: {},ISO resolved to 2019-03-27T10:15 of type java.time.format.Parsed
+    // This is a workaround until the API returns the expected format.
+    public void setDefaultValue(String defaultValue) {
+        if (defaultValue.isEmpty()) {
+            return;
+        }
+        try {
+            this.defaultValue = ZonedDateTime.parse(defaultValue, DEFAULT_VALUE_FORMATTER);
+        } catch (DateTimeParseException ex) {
+            if (defaultValue.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}")) {
+                this.defaultValue = ZonedDateTime.parse(defaultValue + ":00Z", DEFAULT_VALUE_FORMATTER);
+            } else {
+                throw ex;
+            }
+        }
+    }
 }

src/test/resources/com/kintone/client/FieldPropertyDeserializerTest_deserialize_DATETIME.json

@@ -6,7 +6,7 @@
     "noLabel": false,
     "required": false,
     "unique": false,
-    "defaultValue": "2020-01-01T01:30:00.000Z",
+    "defaultValue": "2020-01-01T01:30",
     "defaultNowValue": false
   }
 }