refactor: refactor package protected attribute "propertySet"

Close #151

Author: javier-godoy

src/main/java/com/flowingcode/vaadin/addons/gridexporter/CsvStreamResourceWriter.java

@@ -22,8 +22,6 @@
 
 import com.opencsv.CSVWriter;
 import com.vaadin.flow.component.grid.Grid;
-import com.vaadin.flow.data.binder.BeanPropertySet;
-import com.vaadin.flow.data.binder.PropertySet;
 import com.vaadin.flow.server.VaadinSession;
 import java.io.IOException;
 import java.io.OutputStream;
@@ -92,11 +90,8 @@ public void accept(OutputStream out, VaadinSession session) throws IOException {
     }
   }
 
-  @SuppressWarnings("unchecked")
   private String[] buildRow(T item) {
-    if (exporter.propertySet == null) {
-      exporter.propertySet = (PropertySet<T>) BeanPropertySet.get(item.getClass());
-    }
+
     if (exporter.getColumns().isEmpty()) throw new IllegalStateException("Grid has no columns");
 
     String[] result = new String[exporter.getColumns().size()];

src/main/java/com/flowingcode/vaadin/addons/gridexporter/DocxStreamResourceWriter.java

@@ -23,8 +23,6 @@
 import com.vaadin.flow.component.grid.ColumnTextAlign;
 import com.vaadin.flow.component.grid.Grid;
 import com.vaadin.flow.component.grid.Grid.Column;
-import com.vaadin.flow.data.binder.BeanPropertySet;
-import com.vaadin.flow.data.binder.PropertySet;
 import com.vaadin.flow.data.provider.DataProvider;
 import com.vaadin.flow.server.VaadinSession;
 import java.io.IOException;
@@ -180,16 +178,13 @@ private void fillData(XWPFTable table, XWPFTableCell dataCell, DataProvider<T, ?
         });
   }
 
-  @SuppressWarnings("unchecked")
   private void buildRow(
       T item,
       XWPFTableRow row,
       XWPFTableCell startingCell,
       CTTcPr tcpr,
       XWPFTableCell templateCell) {
-    if (exporter.propertySet == null) {
-      exporter.propertySet = (PropertySet<T>) BeanPropertySet.get(item.getClass());
-    }
+
     if (exporter.getColumns().isEmpty()) {
       throw new IllegalStateException("Grid has no columns");
     }

src/main/java/com/flowingcode/vaadin/addons/gridexporter/ExcelStreamResourceWriter.java

@@ -56,8 +56,6 @@
 import com.vaadin.flow.component.grid.ColumnTextAlign;
 import com.vaadin.flow.component.grid.Grid;
 import com.vaadin.flow.component.grid.Grid.Column;
-import com.vaadin.flow.data.binder.BeanPropertySet;
-import com.vaadin.flow.data.binder.PropertySet;
 import com.vaadin.flow.data.provider.DataProvider;
 import com.vaadin.flow.function.ValueProvider;
 import com.vaadin.flow.server.VaadinSession;
@@ -237,11 +235,8 @@ private int fillData(
     return dataRange.getLastRow();
   }
 
-  @SuppressWarnings("unchecked")
   private void buildRow(T item, Sheet sheet, Cell startingCell) {
-    if (exporter.propertySet == null) {
-      exporter.propertySet = (PropertySet<T>) BeanPropertySet.get(item.getClass());
-    }
+
     if (exporter.getColumns().isEmpty()) {
       throw new IllegalStateException("Grid has no columns");
     }

src/main/java/com/flowingcode/vaadin/addons/gridexporter/GridExporter.java

@@ -30,6 +30,7 @@
 import com.vaadin.flow.component.grid.Grid.Column;
 import com.vaadin.flow.component.html.Anchor;
 import com.vaadin.flow.component.orderedlayout.FlexComponent.JustifyContentMode;
+import com.vaadin.flow.data.binder.BeanPropertySet;
 import com.vaadin.flow.data.binder.PropertyDefinition;
 import com.vaadin.flow.data.binder.PropertySet;
 import com.vaadin.flow.data.renderer.BasicRenderer;
@@ -110,7 +111,7 @@ public class GridExporter<T> implements Serializable {
   String footersPlaceHolder = "${footers}";
 
   List<Grid.Column<T>> columns;
-  PropertySet<T> propertySet;
+  private PropertySet<T> propertySet;
 
   Map<String, String> additionalPlaceHolders = new HashMap<>();
 
@@ -226,6 +227,9 @@ Object extractValueFromColumn(T item, Column<T> column) {
 
     // if there is a key, assume that the property can be retrieved from it
     if (value == null && column.getKey() != null) {
+      if (propertySet == null) {
+        propertySet = (PropertySet<T>) BeanPropertySet.get(item.getClass());
+      }
       Optional<PropertyDefinition<T, ?>> propertyDefinition =
           propertySet.getProperty(column.getKey());
       if (propertyDefinition.isPresent()) {