Shade hadoop compat classes so they can be loaded in hadoop jobs (#13)

hubspot-client-bundles/pom.xml

@@ -74,6 +74,40 @@
                     <pattern>com.google.protobuf</pattern>
                     <shadedPattern>${shade.prefix}.com.google.protobuf</shadedPattern>
                   </relocation>
+                  <!-- 
+                    This is a little brittle, but as far as I can tell this class list hasn't
+                    really changed much. The core problem this solves is that our hadoop jobs
+                    are executed with mapreduce.job.classloader.system.classes set, including
+                    org.apache.hadoop. As a result trying to load any of these classes will
+                    throw ClassNotFoundException because they aren't actually system classes
+                    but are covered by that property. Another option would be to exclude
+                    org.apache.hadoop.metrics2 from the system classes list, but there are a
+                    bunch of classes in there in hadoop and it's hard to know the implications 
+                    of that. So I decided to solve this for hbase by shading these classes
+                    which are brought in by hbase-hadoop-compat and hbase-hadoop2-compat.
+                    These classes are used in snapshot scan jobs, because the metrics are 
+                    initialized when opening an HFile for read.
+                  -->
+                  <relocation>
+                    <pattern>org.apache.hadoop.metrics2</pattern>
+                    <shadedPattern>${shade.prefix}.org.apache.hadoop.metrics2</shadedPattern>
+                    <includes>
+                      <include>org.apache.hadoop.metrics2.MetricHistogram</include>
+                      <include>org.apache.hadoop.metrics2.MetricsExecutor</include>
+                      <include>org.apache.hadoop.metrics2.impl.JmxCacheBuster*</include>
+                      <include>org.apache.hadoop.metrics2.lib.DefaultMetricsSystemHelper</include>
+                      <include>org.apache.hadoop.metrics2.lib.DynamicMetricsRegistry</include>
+                      <include>org.apache.hadoop.metrics2.lib.MetricsExecutorImpl</include>
+                      <include>org.apache.hadoop.metrics2.lib.MetricsExecutorImpl*</include>
+                      <include>org.apache.hadoop.metrics2.lib.MutableFastCounter</include>
+                      <include>org.apache.hadoop.metrics2.lib.MutableHistogram</include>
+                      <include>org.apache.hadoop.metrics2.lib.MutableRangeHistogram</include>
+                      <include>org.apache.hadoop.metrics2.lib.MutableSizeHistogram</include>
+                      <include>org.apache.hadoop.metrics2.lib.MutableTimeHistogram</include>
+                      <include>org.apache.hadoop.metrics2.util.MetricQuantile</include>
+                      <include>org.apache.hadoop.metrics2.util.MetricSampleQuantiles*</include>
+                    </includes>
+                  </relocation>
                 </relocations>
                 <filters>
                   <filter>