Exclude all transitive dependencies of ssj besides commons-math3 and replace linear regression implementation (#638)

Author: dwnusbaum

pom.xml

@@ -63,19 +63,11 @@
       <groupId>ca.umontreal.iro.simul</groupId>
       <artifactId>ssj</artifactId>
       <version>3.3.2</version>
+      <!-- Dependencies are unused, provided by Jenkins core, have unusual licenses, unclear artifact ownership, and/or are obsolete. We only use SmoothingCubicSpline, which does not require dependencies. -->
       <exclusions>
         <exclusion>
-          <groupId>com.google.code.gson</groupId>
-          <artifactId>gson</artifactId>
-        </exclusion>
-        <!-- Provided by Jenkins core -->
-        <exclusion>
-          <groupId>org.jfree</groupId>
-          <artifactId>jcommon</artifactId>
-        </exclusion>
-        <exclusion>
-          <groupId>org.jfree</groupId>
-          <artifactId>jfreechart</artifactId>
+          <groupId>*</groupId>
+          <artifactId>*</artifactId>
         </exclusion>
       </exclusions>
     </dependency>
@@ -104,6 +96,11 @@
       <groupId>io.jenkins.plugins</groupId>
       <artifactId>plugin-util-api</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.apache.commons</groupId>
+      <artifactId>commons-math3</artifactId>
+      <version>3.6.1</version>
+    </dependency>
     <dependency>
       <groupId>org.jenkins-ci.plugins</groupId>
       <artifactId>display-url-api</artifactId>

src/main/java/hudson/tasks/junit/History.java

@@ -46,10 +46,10 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.stream.Collectors;
 import jenkins.util.SystemProperties;
+import org.apache.commons.math3.stat.regression.SimpleRegression;
 import org.kohsuke.accmod.Restricted;
 import org.kohsuke.accmod.restrictions.NoExternalUse;
 import org.kohsuke.stapler.bind.JavaScriptMethod;
-import umontreal.ssj.functionfit.LeastSquares;
 import umontreal.ssj.functionfit.SmoothingCubicSpline;
 
 /**
@@ -248,7 +248,13 @@ private void createLinearTrend(
         if (history.size() < 3) {
             return;
         }
-        double[] cs = LeastSquares.calcCoefficients(lrX, lrY);
+
+        SimpleRegression sr = new SimpleRegression(true);
+        for (int i = 0; i < lrX.length; i++) {
+            sr.addData(lrX[i], lrY[i]);
+        }
+        double intercept = sr.getIntercept();
+        double slope = sr.getSlope();
 
         ObjectNode lrSeries = MAPPER.createObjectNode();
         series.add(lrSeries);
@@ -273,7 +279,7 @@ private void createLinearTrend(
         }
         for (int index = 0; index < history.size(); ++index) {
             // Use float to reduce JSON size.
-            lrData.add((float) (Math.round((cs[0] + index * cs[1]) * roundMul) / roundMul));
+            lrData.add((float) (Math.round((intercept + index * slope) * roundMul) / roundMul));
         }
     }