Combine defaults into a configuration that may already have
user-provided values. Values in src only go into dst if
there is not already a value for that key.
Parameters
dst: any
The destination config object (to be merged into)
name: string
The id of the configuration block to modify (created if doesn't exist)
src: any
The source configuration object (to replace default values in dst}
Combine defaults into a configuration that may already have user-provided values. Values in src only go into dst if there is not already a value for that key.