Change metric to Gauge (#194)

Author: Mrod1598

jmx-metrics/docs/target-systems/tomcat.md

@@ -38,7 +38,7 @@ These metrics are sourced from: https://docs.oracle.com/cd/E11857_01/em.111/e101
 * Description: Maximum time to process a request.
 * Unit: `ms`
 * Labels: `proto_handler`
-* Instrument Type: LongCounterCallback
+* Instrument Type: longValueCallback
 
 * Name: `tomcat.request_count`
 * Description: The total requests.

jmx-metrics/src/integrationTest/java/io/opentelemetry/contrib/jmxmetrics/target_systems/TomcatIntegrationTest.java

@@ -94,7 +94,7 @@ void endToEnd() {
                     attrs.containsOnly(
                         entry("proto_handler", "\"http-nio-8080\""), entry("state", "busy"))),
         metric ->
-            assertSumWithAttributes(
+            assertGaugeWithAttributes(
                 metric,
                 "tomcat.max_time",
                 "Maximum time to process a request.",

jmx-metrics/src/main/resources/target-systems/tomcat.groovy

@@ -27,7 +27,7 @@ otel.instrument(beantomcatrequestProcessor, "tomcat.request_count", "The total r
   "requestCount", otel.&longCounterCallback)
 otel.instrument(beantomcatrequestProcessor, "tomcat.max_time", "Maximum time to process a request.", "ms",
   ["proto_handler" : { mbean -> mbean.name().getKeyProperty("name") }],
-  "maxTime", otel.&longCounterCallback)
+  "maxTime", otel.&longValueCallback)
 otel.instrument(beantomcatrequestProcessor, "tomcat.processing_time", "The total processing time.", "ms",
   ["proto_handler" : { mbean -> mbean.name().getKeyProperty("name") }],
   "processingTime", otel.&longCounterCallback)