Adding log4j2 lookup example for predefined fields

[eyalkoren]

Context: #188

[apmmachine]

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#### Build stats * Start Time: 2022-07-04T07:07:22.834+0000 * Duration: 7 min 47 sec #### Test stats :test_tube: | Test | Results | | ------------ | :-----------------------------: | | Failed | 0 | | Passed | 243 | | Skipped | 0 | | Total | 243 |

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