Wrap up comments for code clarity.

Author: visumickey

firebase-perf/src/main/java/com/google/firebase/perf/metrics/Trace.java

@@ -14,6 +14,8 @@
 
 package com.google.firebase.perf.metrics;
 
+import static com.google.firebase.perf.metrics.validator.PerfMetricValidator.*;
+
 import android.os.Parcel;
 import android.os.Parcelable;
 import androidx.annotation.Keep;
@@ -209,7 +211,7 @@ public void start() {
       return;
     }
 
-    String err = PerfMetricValidator.validateTraceName(name);
+    String err = validateTraceName(name);
 
     if (err != null) {
       logger.error("Cannot start trace '%s'. Trace name is invalid.(%s)", name, err);
@@ -326,7 +328,7 @@ private Counter obtainOrCreateCounterByName(@NonNull String counterName) {
    */
   @Keep
   public void incrementMetric(@NonNull String metricName, long incrementBy) {
-    String err = PerfMetricValidator.validateMetricName(metricName);
+    String err = validateMetricName(metricName);
     if (err != null) {
       logger.error("Cannot increment metric '%s'. Metric name is invalid.(%s)", metricName, err);
       return;
@@ -382,7 +384,7 @@ public long getLongMetric(@NonNull String metricName) {
    */
   @Keep
   public void putMetric(@NonNull String metricName, long value) {
-    String err = PerfMetricValidator.validateMetricName(metricName);
+    String err = validateMetricName(metricName);
     if (err != null) {
       logger.error(
           "Cannot set value for metric '%s'. Metric name is invalid.(%s)", metricName, err);
@@ -639,7 +641,7 @@ private void checkAttribute(@NonNull String key, @NonNull String value) {
               "Exceeds max limit of number of attributes - %d",
               Constants.MAX_TRACE_CUSTOM_ATTRIBUTES));
     }
-    PerfMetricValidator.validateAttribute(new AbstractMap.SimpleEntry<>(key, value));
+    validateAttribute(new AbstractMap.SimpleEntry<>(key, value));
   }
 
   /**

firebase-perf/src/main/java/com/google/firebase/perf/metrics/validator/PerfMetricValidator.java

@@ -145,21 +145,29 @@ public static void validateAttribute(@NonNull Map.Entry<String, String> attribut
     String value = attribute.getValue();
     if (key == null || key.length() == 0) {
       throw new IllegalArgumentException("Attribute key must not be null or empty");
-    } else if (value == null || value.length() == 0) {
+    }
+
+    if (value == null || value.length() == 0) {
       throw new IllegalArgumentException("Attribute value must not be null or empty");
-    } else if (key.length() > Constants.MAX_ATTRIBUTE_KEY_LENGTH) {
+    }
+
+    if (key.length() > Constants.MAX_ATTRIBUTE_KEY_LENGTH) {
       throw new IllegalArgumentException(
           String.format(
               Locale.US,
               "Attribute key length must not exceed %d characters",
               Constants.MAX_ATTRIBUTE_KEY_LENGTH));
-    } else if (value.length() > Constants.MAX_ATTRIBUTE_VALUE_LENGTH) {
+    }
+
+    if (value.length() > Constants.MAX_ATTRIBUTE_VALUE_LENGTH) {
       throw new IllegalArgumentException(
           String.format(
               Locale.US,
               "Attribute value length must not exceed %d characters",
               Constants.MAX_ATTRIBUTE_VALUE_LENGTH));
-    } else if (!key.matches("^(?!(firebase_|google_|ga_))[A-Za-z][A-Za-z_0-9]*")) {
+    }
+
+    if (!key.matches("^(?!(firebase_|google_|ga_))[A-Za-z][A-Za-z_0-9]*")) {
       throw new IllegalArgumentException(
           "Attribute key must start with letter, must only contain alphanumeric characters and"
               + " underscore and must not start with \"firebase_\", \"google_\" and \"ga_");