apm-application-toolkit/apm-toolkit-meter/src/main/java/org/apache/skywalking/apm/toolkit/meter/MeterId.java
apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/meter/MeterId.java

apm-application-toolkit/apm-toolkit-meter/src/main/java/org/apache/skywalking/apm/toolkit/meter/Histogram.java
apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/meter/Histogram.java

apm-application-toolkit/apm-toolkit-opentracing/src/main/java/org/apache/skywalking/apm/toolkit/opentracing/Tag.java
apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/util/KeyValuePair.java