added sigtest to flatlaf-core subproject to check for incompatible API changes in packages com.formdev.flatlaf and com.formdev.flatlaf.util

added FlatLaf 1.6 API signature (generated in clean workspace with gradle task `sigtestGenerate`)

flatlaf-core/build.gradle.kts

@@ -21,10 +21,15 @@ plugins {
 	`flatlaf-publish`
 }
 
+val sigtest = configurations.create( "sigtest" )
+
 dependencies {
 	testImplementation( "org.junit.jupiter:junit-jupiter-api:5.7.2" )
 	testImplementation( "org.junit.jupiter:junit-jupiter-params" )
 	testRuntimeOnly( "org.junit.jupiter:junit-jupiter-engine" )
+
+	// https://github.com/jtulach/netbeans-apitest
+	sigtest( "org.netbeans.tools:sigtest-maven-plugin:1.4" )
 }
 
 java {
@@ -59,10 +64,60 @@ tasks {
 		archiveBaseName.set( "flatlaf" )
 	}
 
+	check {
+		dependsOn( "sigtestCheck" )
+	}
+
 	test {
 		useJUnitPlatform()
 		testLogging.exceptionFormat = org.gradle.api.tasks.testing.logging.TestExceptionFormat.FULL
 	}
+
+	register( "sigtestGenerate" ) {
+		group = "verification"
+		dependsOn( "jar" )
+
+		doLast {
+			ant.withGroovyBuilder {
+				"taskdef"(
+					"name" to "sigtest",
+					"classname" to "org.netbeans.apitest.Sigtest",
+					"classpath" to sigtest.asPath )
+
+				"sigtest"(
+					"action" to "generate",
+					"fileName" to "${project.name}-sigtest.txt",
+					"classpath" to jar.get().outputs.files.asPath,
+					"packages" to "com.formdev.flatlaf,com.formdev.flatlaf.util",
+					"version" to version,
+					"release" to "1.8", // Java version
+					"failonerror" to "true" )
+			}
+		}
+	}
+
+	register( "sigtestCheck" ) {
+		group = "verification"
+		dependsOn( "jar" )
+
+		doLast {
+			ant.withGroovyBuilder {
+				"taskdef"(
+					"name" to "sigtest",
+					"classname" to "org.netbeans.apitest.Sigtest",
+					"classpath" to sigtest.asPath )
+
+				"sigtest"(
+					"action" to "check",
+					"fileName" to "${project.name}-sigtest.txt",
+					"classpath" to jar.get().outputs.files.asPath,
+					"packages" to "com.formdev.flatlaf,com.formdev.flatlaf.util",
+					"version" to version,
+					"release" to "1.8", // Java version
+					"failonerror" to "true" )
+			}
+		}
+	}
 }
 
 flatlafPublish {