OC-258: replace GSON by custom serializer methods (#259)

* OC-258: replace GSON by custom serializer methods; remove all references of GSON (pom.xml, license files, about boxes)

* OC-258: bug fix (objects and arrays were in escaped strings inside quotes)

Author: marek-parfianowicz

clover-all/pom.xml

@@ -88,10 +88,6 @@
             <groupId>it.unimi.dsi</groupId>
             <artifactId>fastutil</artifactId>
         </dependency>
-        <dependency>
-            <groupId>com.google.code.gson</groupId>
-            <artifactId>gson</artifactId>
-        </dependency>
         <dependency>
             <groupId>com.lowagie</groupId>
             <artifactId>itext</artifactId>

clover-core-libs/versions.xml

@@ -7,7 +7,6 @@
     <property name="commons-collections.ver" value="3.2.2"/>
     <property name="commons-lang3.ver" value="3.3.2"/>
     <property name="fastutil.ver" value="4.4.3"/>
-    <property name="gson.ver" value="1.3"/>
     <property name="itext.ver" value="2.0.1"/> <!-- Don't use higher than 2.1.7. Later are based on GPL! -->
     <property name="jcommon.ver" value="1.0.23"/>
     <property name="jdom.ver" value="1.0"/>

clover-core/pom.xml

@@ -74,10 +74,6 @@
             <groupId>jdom</groupId>
             <artifactId>jdom</artifactId>
         </dependency>
-        <dependency>
-            <groupId>com.google.code.gson</groupId>
-            <artifactId>gson</artifactId>
-        </dependency>
         <dependency>
             <groupId>com.lowagie</groupId>
             <artifactId>itext</artifactId>
@@ -345,7 +341,6 @@
                                     <include>commons-lang:commons-lang</include>
                                     <include>org.apache.commons:commons-lang3</include>
                                     <include>it.unimi.dsi:fastutil</include>
-                                    <include>com.google.code.gson:gson</include>
                                     <include>com.lowagie:itext</include>
                                     <include>org.jfree:jcommon</include>
                                     <include>jdom:jdom</include>
@@ -409,13 +404,6 @@
                                         <exclude>build.xml</exclude>
                                     </excludes>
                                 </filter>
-                                <filter>
-                                    <artifact>com.google.code.gson:gson</artifact>
-                                    <excludes>
-                                        <exclude>META-INF/MANIFEST.MF</exclude>
-                                        <exclude>**/assembly-descriptor.xml</exclude>
-                                    </excludes>
-                                </filter>
                                 <filter>
                                     <artifact>org.jfree:jcommon</artifact>
                                     <excludes>
@@ -449,13 +437,6 @@
                                         <include>antlr.**</include>
                                     </includes>
                                 </relocation>
-                                <relocation>
-                                    <pattern>com.google.gson</pattern>
-                                    <shadedPattern>clover.com.google.gson</shadedPattern>
-                                    <includes>
-                                        <include>com.google.gson.**</include>
-                                    </includes>
-                                </relocation>
                                 <relocation>
                                     <pattern>com.lowagie</pattern>
                                     <shadedPattern>clover.com.lowagie</shadedPattern>

clover-core/src/main/java/org/openclover/core/reporters/json/RenderTreeMapJsonAction.java

@@ -1,7 +1,6 @@
 package org.openclover.core.reporters.json;
 
-import com.google.gson.Gson;
-import com.google.gson.GsonBuilder;
+import org.apache.commons.lang3.StringEscapeUtils;
 import org.openclover.core.api.registry.BlockMetrics;
 import org.openclover.core.api.registry.ClassInfo;
 import org.openclover.core.api.registry.HasMetrics;
@@ -16,10 +15,10 @@
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
+import java.util.stream.Collectors;
 
 public class RenderTreeMapJsonAction {
     public static String generateJson(ProjectInfo project, HtmlRenderingSupportImpl renderSupport, boolean classLevel) {
-        final Gson gson = new GsonBuilder().setPrettyPrinting().create();
 
         final List<PackageInfo> pkgInfos = project.getAllPackages();
 
@@ -44,7 +43,46 @@ public static String generateJson(ProjectInfo project, HtmlRenderingSupportImpl
             }
         }
 
-        return gson.toJson(projectNode);
+        return toJsonObject(projectNode);
+    }
+
+    private static String toJsonObject(Node projectNode) {
+        return "{" +
+                toJsonAttr("id", projectNode.id, true) + "," +
+                toJsonAttr("name", projectNode.name, true) + "," +
+                toJsonAttr("data", toJsonObject(projectNode.data), false) + "," +
+                toJsonAttr("children", toJsonArray(projectNode.children), false)
+                + "}";
+    }
+
+    private static String toJsonObject(Data projectNodeData) {
+        return "{" +
+                toJsonAttr("$area", projectNodeData.$area) + "," +
+                toJsonAttr("$color", projectNodeData.$color) + "," +
+                toJsonAttr("path", projectNodeData.path, true) + "," +
+                toJsonAttr("title", projectNodeData.title, true) +
+                "}";
+    }
+
+    private static String toJsonAttr(String name, float value) {
+        return "\"" + name + "\":" + value;
+    }
+
+    private static String toJsonAttr(String name, String value, boolean valueInQuotes) {
+        if (valueInQuotes) {
+            return "\"" + name + "\":\"" + StringEscapeUtils.escapeJson(value) + "\"";
+        } else {
+            return "\"" + name + "\":" + value;
+        }
+    }
+
+    private static String toJsonArray(Collection<Node> projectNodes) {
+        return "[" +
+                projectNodes
+                        .stream()
+                        .map(RenderTreeMapJsonAction::toJsonObject)
+                        .collect(Collectors.joining(",")) +
+                "]";
     }
 
     private static Node createNode(HtmlRenderingSupportImpl renderSupport, int index, String nodeName,