Defines contract for building KeyValueConfigurer instances. The main idea is that it receives Map<String, Any> which holds configuration rules and builds KeyValueConfigurer based on that.

DSL: For simplicity all examples below show YAML config, however, there is no restriction on where it comes from.

Unconditional static configuration

rules:
  key1: value1
  key2: value2

This is the simplest possible configuration - target values are defined for the target keys.

Conditional static configuration with leaf static rules

rules:
  key1:
    - When:
        key2: some-value
      Then: value1
    - When:
        key3: some-other-value
      Then: value2
    - Then: value3

• If key2 = some-value then key1 is set to value1

• Else if key3 = some-other-value then key1 is set to value1

• Else key1 is set to value3

Note: if there is no final unconditional 'Then' clause, then key1 value is not set

Composite AND filter

rules:
  key1:
    - When:
        key2: some-value
      Then: value1
    - When:
        And:
          - key3: some-other-value
          - key4: one-more-value
      Then: value2

Composite OR filter

rules:
  key1:
    - When:
        Or:
          - key2: some-value
          - And:
              key3: some-other-value
              key4: one-more-value
      Then: value

• If key2 = some-value or (key3 = some-other-value and key4 = one-more-value) then key1 is set to value

• Else key1 value is not set/changed

Note: any other filter might be used in AND/OR filters

Dynamic value with static key

rules:
  key1:
    - When:
        key2: 3
      Then: <original-key3>

• If key2 dynamic value = 3 then key is set to key3 dynamic value

• Else key1 value is not set/changed

Note: here and below all elements in angle brackets (<>) mean something dynamic. Here we use a dedicated original- prefix as an indication that dynamic value should be retrieved via target static key

Dynamic value with static key shorthand

rules:
  key1:
    - When:
        key2: 3
      Then: 4
    - Then: <original>

• If key2 = 3 then key1 is set to 4

• Else key1 is set to key1 dynamic value

Note: key1: <original> is the same as key1: <original-key1>

Dynamic value with dynamic key

rules:
  key1:
    - When:
        key2: <flavor1>
      Then: <flavor2>

• If key2 = dynamic value for dynamic key 'flavor1' then key1 is set to dynamic value for dynamic key 'flavor2'

• Else key1 value is not set/changed

Dynamic key

rules:
  key1:
    - When:
        <flow>: flow1
      Then: value1
    - When:
        key2: value2
      Then: value3

• If dynamic value for dynamic key 'flow' is equal to flow then key1 is set to value1

• Else if key2 = value2 then key1 is set to value3

• Else key1 value is not set/changed

Rich string value with dynamic value by static key

rules:
  key1:
    - When:
        key2: 1
      Then: "prefix <original-key3> suffix"

• If key1 type is string and key2 = 1 then set key1 value as string prefix 'dynamic key3 value' suffix

• Else key1 value is not set/changed

Rich string value with dynamic value by dynamic key

rules:
  key1:
    - When:
        key2: 1
      Then: "prefix <flow> suffix"

• If key1 type is string and key2 = 1 then set key1 value as string prefix 'dynamic flow value' suffix

• Else key1 value is not set/changed