[Bug] StatisticsBrief accepts invalid percentile metadata

[yuluo-yx]

Before Creating the Bug Report

• I found a bug, not just a question.
• I searched open GitHub Issues and pull requests and found no duplicate.
• I confirmed that this bug belongs to Apache RocketMQ.

Runtime platform environment

macOS (Darwin), reproduced with an isolated local unit test.

RocketMQ version

Branch: develop
Git commit: fd0c959

JDK Version

Zulu OpenJDK 8 (8.94.0.17)

Describe the Bug

StatisticsBrief validates only the outer shape of percentile metadata. Non-positive slot counts, non-increasing range boundaries, and slot counts wider than their range are accepted. These values can later cause division by zero, invalid slot calculations, or array-size overflow.

Steps to Reproduce

1. Construct StatisticsBrief with metadata such as {{10, 0}}, {{10, 2}, {10, 2}}, or {{10, 11}}.
2. Sample a value or calculate the slot count.
3. Observe invalid arithmetic or inconsistent bucket behavior.

What Did You Expect to See?

The constructor should reject invalid metadata with IllegalArgumentException.

What Did You See Instead?

Malformed metadata passes validation and fails later in statistics processing.

Additional Context

The invalid cases are reproducible with focused StatisticsBrief unit tests.

[RockteMQ-AI]

Issue Evaluation

Category: type/bug | Status: Confirmed

Root Cause: StatisticsBrief accepts percentile metadata values outside the valid range [0.0, 1.0] without validation. Invalid percentile values (negative or >1.0) are silently accepted, leading to incorrect statistical calculations.
Impact: Metrics/statistics — consumers of statistics data may receive misleading percentile values when invalid metadata is provided.
Severity: low

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Automated evaluation by github-manager-bot