Update proguard rules and build configuration

Author: rfc2822

gradle/libs.versions.toml

@@ -1,5 +1,5 @@
 [versions]
-agp = "8.7.3"
+agp = "8.9.1"
 android-desugar = "2.1.5"
 androidx-core = "1.16.0"
 androidx-test-rules = "1.6.1"

lib/build.gradle.kts

@@ -24,6 +24,9 @@ android {
         aarMetadata {
             minCompileSdk = 29
         }
+
+        // These ProGuard/R8 rules will be included in the final APK.
+        consumerProguardFiles("consumer-rules.pro")
     }
 
     compileOptions {
@@ -51,6 +54,15 @@ android {
         }
     }
 
+    buildTypes {
+        release {
+            // Android libraries shouldn't be minified:
+            // https://developer.android.com/studio/projects/android-library#Considerations
+            isMinifyEnabled = false
+            proguardFiles(getDefaultProguardFile("proguard-android-optimize.txt"))
+        }
+    }
+
     lint {
         disable += listOf("AllowBackup", "InvalidPackage")
     }

lib/consumer-rules.pro

@@ -0,0 +1,11 @@
+
+# keep all iCalendar properties/parameters (used via reflection)
+-keep class net.fortuna.ical4j.** { *; }
+
+# don't warn when these are missing
+-dontwarn com.github.erosb.jsonsKema.**
+-dontwarn groovy.**
+-dontwarn java.beans.Transient
+-dontwarn javax.cache.**
+-dontwarn org.codehaus.groovy.**
+-dontwarn org.jparsec.**