@Override
    public void process(boolean validate, boolean documentsOnly) {
        for (SDField field : schema.allConcreteFields()) {
            ScriptExpression script = field.getIndexingScript();
            if (script == null) continue;

            script = (ScriptExpression)new DefaultToCurrentField(field).convert(script);
            script = (ScriptExpression)new EnsureInputExpression(field).convert(script);
            if (validate)
                new VerifyInputExpression(schema, field).visit(script);

            field.setIndexingScript(schema.getName(), script);
        }
    }
This processor modifies all indexing scripts so that they input the value of the owning field by default. It also
ensures that all fields used as input exist.

@author Simon Thoresen Hult
config-model/src/main/java/com/yahoo/schema/processing/IndexingInputs.java