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LOG4J2_UNKNOWN_ARRAY

Summary

  • Rule ID: LOG4J2_UNKNOWN_ARRAY
  • Name: Log4j2 unknown array
  • Problem: Passing unknown arrays into varargs logging calls can produce confusing argument expansion behavior.

What This Rule Reports

This rule reports Log4j2 varargs calls where the provided array arguments are not statically known.

Java Example (reported)

Object[] varOne = methodOne();
LOG.info("value={} {}", varOne);

What This Rule Does Not Report

  • Calls with known array construction/local shape

Java Example (not reported)

Object[] varOne = new Object[] {"a", 1};
LOG.info("value={} {}", varOne);

Prefer explicit arguments or clearly constructed arrays so logging argument structure stays predictable.

Message Shape

Findings explain that an unknown array is passed to a Log4j2 varargs logging call.