feat: add formatter for the date

hale: add new Excel reader parameter that allows to specify import format for date cells
At the moment the formatter has the following format: yyyy-MM-dd, but should be customizable by the user with a new issue.

ING-4151

io/plugins/eu.esdihumboldt.hale.io.xls.test/src/eu/esdihumboldt/hale/io/xls/test/XLSInstanceWriterTestExamples.groovy

@@ -15,6 +15,9 @@
 
 package eu.esdihumboldt.hale.io.xls.test
 
+import java.text.SimpleDateFormat
+import java.time.LocalDate
+
 import eu.esdihumboldt.hale.common.instance.groovy.InstanceBuilder
 import eu.esdihumboldt.hale.common.instance.model.InstanceCollection
 import eu.esdihumboldt.hale.common.schema.groovy.SchemaBuilder
@@ -26,6 +29,11 @@ class XLSInstanceWriterTestExamples {
 
 		Schema schema = createSchema()
 
+		// Declare a date in the "dd/mm/yyyy" format
+		def dateString1 = "25/12/2023"
+		def dateFormat1 = new SimpleDateFormat("dd/MM/yyyy")
+		def date1 = dateFormat1.parse(dateString1)
+
 		// create the instance collection
 		// concrete types are only strings, since the test is not able to choose the correct type in wizard
 		InstanceCollection instances = new InstanceBuilder(types: schema).createCollection {
@@ -59,6 +67,7 @@ class XLSInstanceWriterTestExamples {
 				name('other')
 				number('1')
 				description('other type')
+				date(date1)
 			}
 		}
 	}
@@ -91,9 +100,9 @@ class XLSInstanceWriterTestExamples {
 				name(String)
 				number(String)
 				description(String)
+				date(LocalDate)
 			}
 		}
 		return schema;
 	}
-
 }

io/plugins/eu.esdihumboldt.hale.io.xls/src/eu/esdihumboldt/hale/io/xls/XLSUtil.java

@@ -15,9 +15,15 @@
 
 package eu.esdihumboldt.hale.io.xls;
 
+import java.time.LocalDateTime;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import java.util.Date;
+
 import org.apache.poi.ss.usermodel.Cell;
 import org.apache.poi.ss.usermodel.CellType;
 import org.apache.poi.ss.usermodel.CellValue;
+import org.apache.poi.ss.usermodel.DateUtil;
 import org.apache.poi.ss.usermodel.FormulaEvaluator;
 import org.apache.poi.ss.usermodel.Row;
 import org.apache.poi.ss.usermodel.Sheet;
@@ -30,6 +36,12 @@
  */
 public class XLSUtil {
 
+	/**
+	 * Parameter for the reader specifying how values imported from date cells
+	 * should be formatted.
+	 */
+	public static final String PARAMETER_DATE_FORMAT = "yyyy-MM-dd";
+
 	/**
 	 * Extract the text from a given cell. Formulas are evaluated, for blank or
 	 * error cells <code>null</code> is returned
@@ -65,11 +77,30 @@ public static String extractText(Cell cell, FormulaEvaluator evaluator, Sheet sh
 		case BOOLEAN:
 			return String.valueOf(value.getBooleanValue());
 		case NUMERIC:
-			double number = value.getNumberValue();
-			if (number == Math.floor(number)) {
-				return String.valueOf((int) number);
+			if (DateUtil.isCellDateFormatted(cell)) {
+				// Get the date value from the cell
+				Date dateCellValue = cell.getDateCellValue();
+
+				// Convert java.util.Date to java.time.LocalDateTime
+				LocalDateTime localDateTime = dateCellValue.toInstant()
+						.atZone(ZoneId.systemDefault()).toLocalDateTime();
+
+				// Define a DateTimeFormatter with a specific pattern
+				DateTimeFormatter formatter = DateTimeFormatter.ofPattern(PARAMETER_DATE_FORMAT);
+
+				// Format LocalDateTime using DateTimeFormatter
+				String formattedDate = localDateTime.format(formatter);
+
+				return formattedDate;
+			}
+			else {
+				double number = value.getNumberValue();
+				if (number == Math.floor(number)) {
+					return String.valueOf((int) number);
+				}
+
+				return String.valueOf(value.getNumberValue());
 			}
-			return String.valueOf(value.getNumberValue());
 		case STRING:
 			return value.getStringValue();
 		default: