Refactor: Rename the class and method to make them more descriptive

- Rename from FlowModBuilderHelper to OpenFlowValueMapper
- Rename from UnsupportedConversionException to NoMappingFoundException
- For methods, use "lookup" instead of "convert"

Change-Id: I8e86e3221385a48524247aa78a497b524e16071a
diff --git a/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/NoMappingFoundException.java b/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/NoMappingFoundException.java
new file mode 100644
index 0000000..898b286
--- /dev/null
+++ b/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/NoMappingFoundException.java
@@ -0,0 +1,31 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.provider.of.flow.impl;
+
+/**
+ * Thrown to indicate that no mapping for the input value is found.
+ */
+public class NoMappingFoundException extends RuntimeException {
+    /**
+     * Creates an instance with the specified values.
+     *
+     * @param input input value of mapping causing this exception
+     * @param output the desired class which the input value is mapped to
+     */
+    public NoMappingFoundException(Object input, Class<?> output) {
+        super(String.format("No mapping found for %s when converting to %s", input, output.getName()));
+    }
+}