Merge PR #408: Update prometheus-client-bridge module to follow style guide

Author: trask

prometheus-client-bridge/src/main/java/io/opentelemetry/contrib/metrics/prometheus/clientbridge/MetricAdapter.java

@@ -6,6 +6,8 @@
 package io.opentelemetry.contrib.metrics.prometheus.clientbridge;
 
 import static io.prometheus.client.Collector.doubleToGoString;
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.NANOSECONDS;
 
 import io.opentelemetry.api.common.Attributes;
 import io.opentelemetry.api.trace.SpanContext;
@@ -28,7 +30,6 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
-import java.util.concurrent.TimeUnit;
 import java.util.function.Function;
 import javax.annotation.Nullable;
 
@@ -54,6 +55,8 @@ final class MetricAdapter {
   static final String LABEL_NAME_QUANTILE = "quantile";
   static final String LABEL_NAME_LE = "le";
 
+  static final Function<String, String> sanitizer = new NameSanitizer();
+
   // Converts a MetricData to a Prometheus MetricFamilySamples.
   static MetricFamilySamples toMetricFamilySamples(MetricData metricData) {
     String cleanMetricName = cleanMetricName(metricData.getName());
@@ -99,8 +102,6 @@ static Collector.Type toMetricFamilyType(MetricData metricData) {
     return Collector.Type.UNKNOWN;
   }
 
-  static final Function<String, String> sanitizer = new NameSanitizer();
-
   // Converts a list of points from MetricData to a list of Prometheus Samples.
   static List<Sample> toSamples(
       String name, MetricDataType type, Collection<? extends PointData> points) {
@@ -291,15 +292,15 @@ private static Sample createSample(
           labelValues,
           value,
           toPrometheusExemplar(exemplar),
-          TimeUnit.MILLISECONDS.convert(timestampNanos, TimeUnit.NANOSECONDS));
+          MILLISECONDS.convert(timestampNanos, NANOSECONDS));
     }
     return new Sample(
         name,
         labelNames,
         labelValues,
         value,
         null,
-        TimeUnit.MILLISECONDS.convert(timestampNanos, TimeUnit.NANOSECONDS));
+        MILLISECONDS.convert(timestampNanos, NANOSECONDS));
   }
 
   private static io.prometheus.client.exemplars.Exemplar toPrometheusExemplar(
@@ -309,7 +310,7 @@ private static io.prometheus.client.exemplars.Exemplar toPrometheusExemplar(
       return new io.prometheus.client.exemplars.Exemplar(
           getExemplarValue(exemplar),
           // Convert to ms for prometheus, truncate nanosecond precision.
-          TimeUnit.NANOSECONDS.toMillis(exemplar.getEpochNanos()),
+          NANOSECONDS.toMillis(exemplar.getEpochNanos()),
           "trace_id",
           spanContext.getTraceId(),
           "span_id",

prometheus-client-bridge/src/main/java/io/opentelemetry/contrib/metrics/prometheus/clientbridge/PrometheusCollector.java

@@ -5,6 +5,8 @@
 
 package io.opentelemetry.contrib.metrics.prometheus.clientbridge;
 
+import static java.util.Collections.unmodifiableList;
+
 import io.opentelemetry.sdk.common.CompletableResultCode;
 import io.opentelemetry.sdk.metrics.InstrumentType;
 import io.opentelemetry.sdk.metrics.data.AggregationTemporality;
@@ -15,7 +17,6 @@
 import io.prometheus.client.CollectorRegistry;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
 import java.util.function.Supplier;
 
@@ -79,7 +80,7 @@ public List<MetricFamilySamples> collect() {
       for (MetricData metricData : allMetrics) {
         allSamples.add(MetricAdapter.toMetricFamilySamples(metricData));
       }
-      return Collections.unmodifiableList(allSamples);
+      return unmodifiableList(allSamples);
     }
   }
 }

prometheus-client-bridge/src/main/java/io/opentelemetry/contrib/metrics/prometheus/clientbridge/Serializer.java

@@ -21,11 +21,12 @@
 
 package io.opentelemetry.contrib.metrics.prometheus.clientbridge;
 
+import static java.util.Collections.emptyList;
+
 import io.opentelemetry.sdk.metrics.data.HistogramPointData;
 import io.opentelemetry.sdk.metrics.data.MetricData;
 import io.opentelemetry.sdk.metrics.data.PointData;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
 
 /** Serializes metrics into Prometheus exposition formats. */
@@ -71,7 +72,7 @@ static Collection<? extends PointData> getPoints(MetricData metricData) {
       case EXPONENTIAL_HISTOGRAM:
         return metricData.getExponentialHistogramData().getPoints();
     }
-    return Collections.emptyList();
+    return emptyList();
   }
 
   private Serializer() {}