Consider the following example from Knime:   in which the joiner processor knows what columns it receives from its incoming relationships (e.g., country). If one wants to implement such functionality for NiFi (e.g., in a custom Processor UI), can he obtain information about a processor's preceding processors in the pipeline (e.g., the schema of the output of the processors)? Note that we need the information in the phase of defining the pipeline not when the pipeline is executed. ... View more