From BaseVariant's source: https://android.googlesource.com/platform/tools/base/+/master/build-system/gradle-core/src/main/groovy/com/android/build/gradle/api/BaseVariant.java

gistfile1.java

/**
 * Returns the Java Compilation task if javac was configured to compile the source files.
 * @deprecated prefer {@link #getJavaCompiler} which always return the java compiler task
 * irrespective of which tool chain (javac or jack) used.
 */
@Nullable
@Deprecated
JavaCompile getJavaCompile() throws IllegalStateException;

/**
 * Returns the Java Compiler task which can be either javac or jack depending on the project
 * configuration.
 */
@NonNull
AbstractCompile getJavaCompiler();