Microseconds support added

Author: robsunday

instrumentation/jmx-metrics/library/src/main/java/io/opentelemetry/instrumentation/jmx/engine/unit/UnitConverterFactory.java

@@ -16,6 +16,7 @@ public class UnitConverterFactory {
 
   static {
     registerConverter("ms", "s", value -> value.doubleValue() / TimeUnit.SECONDS.toMillis(1), true);
+    registerConverter("us", "s", value -> value.doubleValue() / TimeUnit.SECONDS.toMicros(1), true);
     registerConverter("ns", "s", value -> value.doubleValue() / TimeUnit.SECONDS.toNanos(1), true);
   }
 

instrumentation/jmx-metrics/library/src/test/java/io/opentelemetry/instrumentation/jmx/engine/unit/UnitConverterFactoryTest.java

@@ -24,6 +24,10 @@ class UnitConverterFactoryTest {
     "25,ns, 0.000000025",
     "96614101945,ns, 96.614101945",
     "0,ns, 0",
+    "1000000,us, 1.0",
+    "25,us, 0.000025",
+    "96614101945,us, 96614.101945",
+    "0,ns, 0",
     "1000,ms, 1.0",
     "25,ms, 0.025",
     "9661410,ms, 9661.41",