public Builder withTaskDefinition(TaskDef val) {
            taskDefinition = val;
            return this;
        }
Sets the {@code taskDefinition} and returns a reference to this Builder so that the
methods can be chained together.

@param val the {@code taskDefinition} to set
@return a reference to this Builder
core/src/main/java/com/netflix/conductor/core/execution/mapper/TaskMapperContext.java