Fixed a lot of logic, replaced Files with Documents

Lab3/src/main/java/org/lumijiez/interfaces/IDocument.java

@@ -5,8 +5,10 @@ import org.lumijiez.enums.FileType;
 import java.util.Date;
 
 public interface IDocument {
-    public String getExtension();
-    public Date getCreatedTime();
-    public Date getModificationTime();
-    public FileType getFileType();
+    String getExtension();
+    Date getCreatedTime();
+    Date getModificationTime();
+    FileType getFileType();
+    long getFilesizeKB();
+    String getInfo();
 }