style: sonarqube issues

Signed-off-by: Thibault Meyer <meyer.thibault@gmail.com>

Author: thibaultmeyer

src/test/java/io/github/thibaultmeyer/cuid/HistogramTest.java

@@ -1,5 +1,6 @@
 package io.github.thibaultmeyer.cuid;
 
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.MethodOrderer;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.TestMethodOrder;
@@ -30,6 +31,7 @@ void histogramCUIDv1() {
         final Map<Integer, Integer> frequencies = histogram.histogram(20);
 
         // Assert
+        Assertions.assertNotNull(frequencies);
         System.out.println("CUID v1: " + frequencies);
     }
 
@@ -48,6 +50,7 @@ void histogramCUIDv2() {
         final Map<Integer, Integer> frequencies = histogram.histogram(20);
 
         // Assert
+        Assertions.assertNotNull(frequencies);
         System.out.println("CUID v2: " + frequencies);
     }
 

src/test/java/io/github/thibaultmeyer/cuid/PerformanceTest.java

@@ -14,7 +14,7 @@
 final class PerformanceTest {
 
     @BeforeAll
-    public static void beforeAll() {
+    static void beforeAll() {
 
         System.gc();
     }