Test and Display if maven isn't installed

build.sh

@@ -29,6 +29,15 @@
 #
 #   mvn -version
 #
+# NOTE: If this command returns:
+#
+#     -bash: mvn: command not found
+#
+# You either didn't install maven or it isn't in your path
+# i.e.
+#     which mvn
+#     /usr/local/bin/mvn
+#
 # 2. Check which version of the Java JRE is installed:
 #
 #   java -version
@@ -88,6 +97,13 @@
 #
 # As the source code is using Java 1.8 langauge features.
 
+if [[ -z "$(which mvn)" ]]; then
+    echo "ERROR: Maven isn't installed"
+    echo "Install via:"
+    echo "   brew install maven"
+    exit
+fi
+
 if [[ -z "$JAVA_HOME" ]]; then
     echo "WARNING: JAVA_HOME was not set"
     echo "... Defaulting to Java 1.8..."