Replace slf4j-reload4j if log4j-slf4j2-impl is on the classpath for Spring Boot applications

Author: asibross

src/integTest/groovy/nebula/plugin/resolutionrules/SpringBootLog4j2Spec.groovy

@@ -0,0 +1,47 @@
+package nebula.plugin.resolutionrules
+
+class SpringBootLog4j2Spec extends RulesBaseSpecification {
+
+    def setup() {
+        def ruleFile = new File(getClass().getResource('/optional-spring-boot-log4j2.json').toURI())
+        buildFile << """\
+            dependencies {
+                resolutionRules files('${ruleFile.absolutePath}')
+            }
+            
+            nebulaResolutionRules {
+                optional = ['spring-boot-log4j2']
+            }
+            """.stripIndent()
+    }
+
+    def 'check slf4j-reload4j replacement works'() {
+        buildFile << '''\
+            dependencies {
+                implementation 'org.slf4j:slf4j-reload4j:latest.release'
+                implementation 'org.apache.logging.log4j:log4j-slf4j2-impl:latest.release'
+            }
+            '''.stripIndent()
+
+        when:
+        def result = runWithArgumentsSuccessfully('dependencies', '--configuration', 'compileClasspath')
+
+        then:
+        result.output.contains 'org.slf4j:slf4j-reload4j:latest.release -> org.apache.logging.log4j:log4j-slf4j2-impl:'
+    }
+
+    def 'leaves slf4j-reload4j if log4j-slf4j2-impl is not present'() {
+        buildFile << '''\
+            dependencies {
+                implementation 'org.slf4j:slf4j-reload4j:latest.release'
+            }
+            '''.stripIndent()
+
+        when:
+        def result = runWithArgumentsSuccessfully('dependencies', '--configuration', 'compileClasspath')
+
+        then:
+        !result.output.contains('org.slf4j:slf4j-reload4j:latest.release -> org.apache.logging.log4j:log4j-slf4j2-impl:')
+    }
+
+}

src/main/resources/optional-spring-boot-log4j2.json

@@ -14,6 +14,13 @@
             "reason" : "Spring Boot Log4J 2 configuration",
             "author" : "Danny Thomas",
             "date" : "2018-10-30"
+        },
+        {
+            "module" : "org.slf4j:slf4j-reload4j",
+            "with" : "org.apache.logging.log4j:log4j-slf4j2-impl",
+            "reason" : "Spring Boot Log4J 2 configuration",
+            "author" : "Asi Bross",
+            "date" : "2025-05-30"
         }
     ],
     "align": [],