diff --git a/checkstyle.xml b/checkstyle.xml
index 5877ec9..828cdaa 100644
--- a/checkstyle.xml
+++ b/checkstyle.xml
@@ -100,7 +100,7 @@
 
         <!-- Checks for imports                              -->
         <!-- See http://checkstyle.sf.net/config_import.html -->
-        <!--<module name="AvoidStarImport"/>-->
+        <module name="AvoidStarImport"/>
         <module name="IllegalImport"/> <!-- defaults to sun.* packages -->
         <module name="RedundantImport"/>
         <!--module name="UnusedImports">
@@ -136,7 +136,7 @@
         <module name="AvoidNestedBlocks"/>
         <module name="EmptyBlock"/>
         <module name="LeftCurly"/>
-        <!--<module name="NeedBraces"/>-->
+        <module name="NeedBraces"/>
         <module name="RightCurly"/>
 
         <!-- Checks for common coding problems               -->
diff --git a/src/main/java/ru/ulstu/core/model/BaseEntity.java b/src/main/java/ru/ulstu/core/model/BaseEntity.java
index bd0f1e4..d3dfa76 100644
--- a/src/main/java/ru/ulstu/core/model/BaseEntity.java
+++ b/src/main/java/ru/ulstu/core/model/BaseEntity.java
@@ -1,6 +1,10 @@
 package ru.ulstu.core.model;
 
-import javax.persistence.*;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.MappedSuperclass;
+import javax.persistence.Version;
 import java.io.Serializable;
 
 @MappedSuperclass
diff --git a/src/main/java/ru/ulstu/core/util/DateUtils.java b/src/main/java/ru/ulstu/core/util/DateUtils.java
index b24b09c..6122583 100644
--- a/src/main/java/ru/ulstu/core/util/DateUtils.java
+++ b/src/main/java/ru/ulstu/core/util/DateUtils.java
@@ -1,6 +1,11 @@
 package ru.ulstu.core.util;
 
-import java.time.*;
+import java.time.Instant;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.time.Month;
+import java.time.ZoneId;
 import java.util.Arrays;
 import java.util.Calendar;
 import java.util.Date;
@@ -24,7 +29,7 @@ public class DateUtils {
         return cal;
     }
 
-    public static List<Month> getMonths () {
+    public static List<Month> getMonths() {
         return Arrays.asList(Month.values());
     }
 
diff --git a/src/main/java/ru/ulstu/file/model/FileData.java b/src/main/java/ru/ulstu/file/model/FileData.java
index 08445a3..3f97130 100644
--- a/src/main/java/ru/ulstu/file/model/FileData.java
+++ b/src/main/java/ru/ulstu/file/model/FileData.java
@@ -20,7 +20,7 @@ public class FileData extends BaseEntity {
     private byte[] data;
 
     @Column(name = "is_latex_attach")
-    private boolean isLatexAttach;
+    private Boolean isLatexAttach;
 
     public String getName() {
         return name;
@@ -54,11 +54,11 @@ public class FileData extends BaseEntity {
         this.data = data;
     }
 
-    public boolean isLatexAttach() {
+    public Boolean isLatexAttach() {
         return isLatexAttach;
     }
 
-    public void setLatexAttach(boolean latexAttach) {
+    public void setLatexAttach(Boolean latexAttach) {
         isLatexAttach = latexAttach;
     }
 }
diff --git a/src/main/java/ru/ulstu/file/model/FileDataDto.java b/src/main/java/ru/ulstu/file/model/FileDataDto.java
index 65ef275..e83bf12 100644
--- a/src/main/java/ru/ulstu/file/model/FileDataDto.java
+++ b/src/main/java/ru/ulstu/file/model/FileDataDto.java
@@ -9,7 +9,7 @@ public class FileDataDto {
     private String fileName;
     private String tmpFileName;
     private boolean deleted;
-    private boolean isLatexAttach;
+    private Boolean isLatexAttach;
 
     public FileDataDto() {
     }
@@ -17,7 +17,7 @@ public class FileDataDto {
     @JsonCreator
     public FileDataDto(@JsonProperty("id") Integer id,
                        @JsonProperty("name") String name,
-                       @JsonProperty("isLatexAttach") boolean isLatexAttach,
+                       @JsonProperty("isLatexAttach") Boolean isLatexAttach,
                        @JsonProperty("fileName") String fileName,
                        @JsonProperty("tmpFileName") String tmpFileName) {
         this.id = id;
@@ -77,19 +77,19 @@ public class FileDataDto {
         this.deleted = deleted;
     }
 
-    public boolean isLatexAttach() {
+    public Boolean isLatexAttach() {
         return isLatexAttach;
     }
 
-    public boolean getIsLatexAttach() {
+    public Boolean getIsLatexAttach() {
         return isLatexAttach;
     }
 
-    public void setLatexAttach(boolean latexAttach) {
+    public void setLatexAttach(Boolean latexAttach) {
         isLatexAttach = latexAttach;
     }
 
-    public void setIsLatexAttach(boolean latexAttach) {
+    public void setIsLatexAttach(Boolean latexAttach) {
         isLatexAttach = latexAttach;
     }
 }
diff --git a/src/main/java/ru/ulstu/file/service/FileService.java b/src/main/java/ru/ulstu/file/service/FileService.java
index 3a0a87c..4bb1658 100644
--- a/src/main/java/ru/ulstu/file/service/FileService.java
+++ b/src/main/java/ru/ulstu/file/service/FileService.java
@@ -127,7 +127,7 @@ public class FileService {
     public void createLatexAttachs(PaperDto paper) throws IOException {
         for (FileDataDto fileDataDto : paper.getFiles()
                 .stream()
-                .filter(f -> f.isLatexAttach() && !f.isDeleted())
+                .filter(f -> (f.isLatexAttach() != null && f.isLatexAttach()) && !f.isDeleted())
                 .collect(Collectors.toList())) {
             if (fileDataDto.getId() == null) {
                 File oldFile = getTmpFilePath(fileDataDto.getTmpFileName()).toFile();
diff --git a/src/main/java/ru/ulstu/odin/model/OdinField.java b/src/main/java/ru/ulstu/odin/model/OdinField.java
index 5917a44..c60c945 100644
--- a/src/main/java/ru/ulstu/odin/model/OdinField.java
+++ b/src/main/java/ru/ulstu/odin/model/OdinField.java
@@ -31,14 +31,13 @@ public abstract class OdinField implements Comparable {
             return this.name().toLowerCase();
         }
     }
-
-    private Field field;
     protected final OdinFieldType fieldType;
     protected final String fieldName;
     protected final String caption;
     protected final OdinVisible.OdinVisibleType visible;
     protected final boolean readOnly;
     protected final boolean notEmpty;
+    private Field field;
 
     public OdinField(Field field, OdinFieldType fieldType) {
         this.field = field;
@@ -126,8 +125,12 @@ public abstract class OdinField implements Comparable {
 
     @Override
     public boolean equals(Object o) {
-        if (this == o) return true;
-        if (o == null || getClass() != o.getClass()) return false;
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
         OdinField odinField = (OdinField) o;
         return Objects.equals(fieldName, odinField.fieldName);
     }
diff --git a/src/main/java/ru/ulstu/paper/service/LatexService.java b/src/main/java/ru/ulstu/paper/service/LatexService.java
index 6bf5226..82dd1ba 100644
--- a/src/main/java/ru/ulstu/paper/service/LatexService.java
+++ b/src/main/java/ru/ulstu/paper/service/LatexService.java
@@ -12,11 +12,11 @@ import java.nio.file.Files;
 
 @Service
 public class LatexService {
+    private final String pdfLatexError = "Errors occurred while executing pdfLaTeX.";
+    private final String bibtexError = "Errors occurred while executing bibtex.";
     private String errorMessage;
     private File pdfFile;
     private FileService fileService;
-    private final String pdfLatexError = "Errors occurred while executing pdfLaTeX.";
-    private final String bibtexError = "Errors occurred while executing bibtex.";
 
     public LatexService(FileService fileService) {
         this.fileService = fileService;
@@ -42,7 +42,9 @@ public class LatexService {
         InputStreamReader inputStreamReader = new InputStreamReader(process.getInputStream());
 
         try (BufferedReader bufferedReader = new BufferedReader(inputStreamReader)) {
-            while ((bufferedReader.readLine()) != null) ;
+            while ((bufferedReader.readLine()) != null) {
+                //
+            }
         }
 
         int exitCode = process.waitFor();
@@ -55,16 +57,18 @@ public class LatexService {
     private boolean generate(String filename, File dir) throws IOException, InterruptedException {
         startProcess(new String[]{"pdflatex", filename, "--interaction=nonstopmode"}, dir, pdfLatexError);
         startProcess(new String[]{"bibtex", filename}, dir, bibtexError);
-        if (startProcess(new String[]{"pdflatex", filename, "--interaction=nonstopmode"}, dir, pdfLatexError) != 0)
+        if (startProcess(new String[]{"pdflatex", filename, "--interaction=nonstopmode"}, dir, pdfLatexError) != 0) {
             return false;
+        }
         return checkPdf(filename, dir);
     }
 
     private boolean checkPdf(String filename, File dir) {
         pdfFile = new File(dir.getAbsolutePath() + File.separator + filename + ".pdf");
 
-        if (pdfFile.isFile()) return true;
-        else {
+        if (pdfFile.isFile()) {
+            return true;
+        } else {
             errorMessage = "The pdf file could not be created.";
             return false;
         }
diff --git a/src/main/java/ru/ulstu/students/controller/TaskController.java b/src/main/java/ru/ulstu/students/controller/TaskController.java
index 8fd9575..50cb052 100644
--- a/src/main/java/ru/ulstu/students/controller/TaskController.java
+++ b/src/main/java/ru/ulstu/students/controller/TaskController.java
@@ -3,7 +3,11 @@ package ru.ulstu.students.controller;
 import org.springframework.stereotype.Controller;
 import org.springframework.ui.ModelMap;
 import org.springframework.validation.Errors;
-import org.springframework.web.bind.annotation.*;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.ModelAttribute;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
 import ru.ulstu.deadline.model.Deadline;
 import ru.ulstu.students.model.Task;
 import ru.ulstu.students.model.TaskDto;
@@ -16,7 +20,9 @@ import java.util.List;
 import java.util.stream.Collectors;
 
 import static org.springframework.util.StringUtils.isEmpty;
-import static ru.ulstu.students.controller.Navigation.*;
+import static ru.ulstu.students.controller.Navigation.REDIRECT_TO;
+import static ru.ulstu.students.controller.Navigation.TASKS_PAGE;
+import static ru.ulstu.students.controller.Navigation.TASK_PAGE;
 
 @Controller()
 @RequestMapping(value = "/students")
diff --git a/src/main/java/ru/ulstu/students/model/Task.java b/src/main/java/ru/ulstu/students/model/Task.java
index be1b1c6..c4d7409 100644
--- a/src/main/java/ru/ulstu/students/model/Task.java
+++ b/src/main/java/ru/ulstu/students/model/Task.java
@@ -7,7 +7,19 @@ import ru.ulstu.core.model.BaseEntity;
 import ru.ulstu.deadline.model.Deadline;
 import ru.ulstu.tags.model.Tag;
 
-import javax.persistence.*;
+import javax.persistence.CascadeType;
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.EnumType;
+import javax.persistence.Enumerated;
+import javax.persistence.FetchType;
+import javax.persistence.JoinColumn;
+import javax.persistence.JoinTable;
+import javax.persistence.ManyToMany;
+import javax.persistence.OneToMany;
+import javax.persistence.OrderBy;
+import javax.persistence.Temporal;
+import javax.persistence.TemporalType;
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.List;
diff --git a/src/main/java/ru/ulstu/user/model/UserSession.java b/src/main/java/ru/ulstu/user/model/UserSession.java
index 1eb761d..50fec65 100644
--- a/src/main/java/ru/ulstu/user/model/UserSession.java
+++ b/src/main/java/ru/ulstu/user/model/UserSession.java
@@ -2,7 +2,13 @@ package ru.ulstu.user.model;
 
 import ru.ulstu.core.model.BaseEntity;
 
-import javax.persistence.*;
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.JoinColumn;
+import javax.persistence.ManyToOne;
+import javax.persistence.Table;
+import javax.persistence.Temporal;
+import javax.persistence.TemporalType;
 import javax.validation.constraints.NotNull;
 import java.util.Date;
 
diff --git a/src/main/resources/templates/papers/fragments/paperFilesListFragment.html b/src/main/resources/templates/papers/fragments/paperFilesListFragment.html
index fcc875c..5934c59 100644
--- a/src/main/resources/templates/papers/fragments/paperFilesListFragment.html
+++ b/src/main/resources/templates/papers/fragments/paperFilesListFragment.html
@@ -8,7 +8,7 @@
 <div th:fragment="filesList (isLatexAttach)" th:remove="tag">
     <th:block th:each="file, rowStat : *{files}">
 
-        <span th:if="${file.isLatexAttach == isLatexAttach}" th:remove="tag">
+        <span th:if="${(!isLatexAttach and file.isLatexAttach == null) or file.isLatexAttach == isLatexAttach}" th:remove="tag">
 
             <div class="row" th:id="|files${rowStat.index}|"
                  th:style="${file.deleted} ? 'display: none;' :''">