Replace Mockito when with doReturn in Micrometer tests (#1709)

Author: eyalkoren

apm-agent-plugins/apm-micrometer-plugin/src/test/java/co/elastic/apm/agent/micrometer/MicrometerInstrumentationTest.java

@@ -42,7 +42,7 @@
 import java.util.List;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.mockito.Mockito.when;
+import static org.mockito.Mockito.doReturn;
 
 class MicrometerInstrumentationTest {
 
@@ -54,7 +54,7 @@ class MicrometerInstrumentationTest {
     @BeforeEach
     void setUp() {
         config = SpyConfiguration.createSpyConfig();
-        when(config.getConfig(ReporterConfiguration.class).getMetricsIntervalMs()).thenReturn(50L);
+        doReturn(50L).when(config.getConfig(ReporterConfiguration.class)).getMetricsIntervalMs();
         reporter = new MockReporter();
         lastMeasuredMetricSetNumber = 0;
         lastFooSamples = 0;
@@ -75,7 +75,7 @@ void testRegisterMeterRegistry() {
 
     @Test
     void testReportedWhenInstrumentConfigDisabled() {
-        when(config.getConfig(CoreConfiguration.class).isInstrument()).thenReturn(false);
+        doReturn(false).when(config.getConfig(CoreConfiguration.class)).isInstrument();
         ElasticApmAgent.initInstrumentation(MockTracer.createRealTracer(reporter, config), ByteBuddyAgent.install());
         SimpleMeterRegistry registry = new SimpleMeterRegistry();
         registry.counter("foo").increment();

apm-agent-plugins/apm-micrometer-plugin/src/test/java/co/elastic/apm/agent/micrometer/MicrometerMetricsReporterTest.java

@@ -60,7 +60,6 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.doReturn;
-import static org.mockito.Mockito.when;
 
 
 class MicrometerMetricsReporterTest {
@@ -133,7 +132,7 @@ void testDedotMetricName() {
 
     @Test
     void testDisableDedotMetricName() {
-        when(tracer.getConfig(MetricsConfiguration.class).isDedotCustomMetrics()).thenReturn(false);
+        doReturn(false).when(tracer.getConfig(MetricsConfiguration.class)).isDedotCustomMetrics();
         meterRegistry.counter("foo.bar").increment(42);
 
         JsonNode metricSet = getSingleMetricSet();